- populate the database with some data when testing migrations
- try both one-step and two-step migrations (`SKIP_POST_DEPLOYMENT_MIGRATIONS`)

Fix regression from #16896

Under certain conditions, files fetched from remotes trigger an error when
being uploaded using OpenStack Swift. This is because in some cases, the
remote server will not return a content-length, so our ResponseWithLimitAdapter
will hold a `nil` value for `#size`, which will lead to an invalid value
for the Content-Length header of the Swift API call.

This commit fixes that by taking the size from the actually-downloaded file
size rather than the upstream-provided Content-Length header value.

* Change references to tootsuite/mastodon to mastodon/mastodon

* Remove obsolete test fixture

* Replace occurrences of tootsuite/mastodon with mastodon/mastodon in CHANGELOG

And a few other places

* Do not block existing users' emails on self-destruct

That is wasteful and unintuitive

* Do not close registrations when running tootctl self-destruct with --dry-run

* Close registrations on self-destruct regardless of known remote accounts

* Fix tootctl self-destruct not sending Deletes for recently-suspended accounts

* Suspend local users even if no remote account is known

* Do not show scary confirmation text if ran with --dry-run

In order to work around https://github.com/mastodon/mastodon/issues/16895,
add a warning to .env.production.sample, and change the mastodon:setup rake
task to:
- output a warning if a variable will be interpreted differently by dotenv
  and docker-compose
- ensure the printed config is compatible with docker-compose

* Fix migration script not being able to run if it fails midway

* Fix old migration script

* Fix old migration script

* Refactor CorruptionError

* Fix account deletion sometimes failing because of optimistic locks

In some rare occasions[1], deleting accounts would fail with a
`StaleObjectError` exception.

Indeed, account deletion manually sets the `AccountStat` values without
handling cases where the optimistic locking on `AccountStat` would fail.

To my knowledge, with the rewrite of account counters in #15913, the
`DeleteAccountService` is now the only place that changes the counters in
a way that is not atomic.

Since in this specific case, we do not care about the previous values of the
account counters, it appears we don't need locking at all for this table
anymore.

[1]: https://discourse.joinmastodon.org/t/account-cant-be-deleted/3602

* Bump MAX_SUPPORTED_VERSION in maintenance script

Fixes #16344

* Update maintenance script to support latest database migrations

* Update Account#merge_with!

* Fix issues with POSIX::Spawn, Terrapin and Ruby 3.0

Also improve the Terrapin monkey-patch for the stderr/stdout issue.

* Fix keyword argument handling throughout the codebase

* Monkey-patch Paperclip to fix keyword arguments handling in validators

* Change validation_extensions to please CodeClimate

* Bump microformats from 4.2.1 to 4.3.1

* Allow Ruby 3.0

* Add Ruby 3.0 test target to CircleCI

* Add test for admin dashboard warnings

* Fix admin dashboard warnings on Ruby 3.0

* Fix media processing getting stuck on too much stdin/stderr

See thoughtbot/terrapin#5

* Remove dependency on paperclip-av-transcoder gem

* Remove dependency on streamio-ffmpeg gem

* Disable stdin on ffmpeg process

* Fix how to change connection pool for rails 6

* Fix to match the code elsewhere

occured -> occurred

* Update devise-two-factor to unreleased fork for Rails 6 support

Update tests to match new `rotp` version.

* Update nsa gem to unreleased fork for Rails 6 support

* Update rails to 6.1.3 and rails-i18n to 6.0

* Update to unreleased fork of pluck_each for Ruby 6 support

* Run "rails app:update"

* Add missing ActiveStorage config file

* Use config.ssl_options instead of removed ApplicationController#force_ssl

Disabled force_ssl-related tests as they do not seem to be easily testable
anymore.

* Fix nonce directives by removing Rails 5 specific monkey-patching

* Fix fixture_file_upload deprecation warning

* Fix yield-based test failing with Rails 6

* Use Rails 6's index_with when possible

* Use ActiveRecord::Cache::Store#delete_multi from Rails 6

This will yield better performances when deleting an account

* Disable Rails 6.1's automatic preload link headers

Since Rails 6.1, ActionView adds preload links for javascript files
in the Links header per default.

In our case, that will bloat headers too much and potentially cause
issues with reverse proxies. Furhermore, we don't need those links,
as we already output them as HTML link tags.

* Switch to Rails 6.0 default config

* Switch to Rails 6.1 default config

* Do not include autoload paths in the load path

It appears assets are built during image build, and they shouldn't need
to be rebuilt, since we now have reproducible builds.

* Improve account counters handling

* Use ActiveRecord::Base::sanitize_sql to pass values instead of interpolating them

Keep using string interpolation for `key` as it is safe and using
“ActiveRecord::Base::sanitize_sql_hash_for_assignment” would require stitching
bits of SQL in a way that is not more easily checked for safety.

* Add migration hook to catch PostgreSQL versions earlier than 9.5

Mastodon::MigrationHelpers has been forked from Gitlab a long time ago, but
Mastodon has never supported using a MySQL database.

Removing MySQL support from Mastodon::MigrationHelpers makes it a little easier
to maintain. In particular, it removes code that would need updating with
Rails 6.

Hopefully fixes #15922

Also update support up to latest database schema version

* Use ActiveRecord::Result#to_ary instead of deprecated to_hash

They do the same thing, and to_hash has been removed from Rails 6.1

* Explicitly name polymorphic indexes to workaround a bug in Rails 6.1

cf. https://github.com/rails/rails/issues/41693

* Fix incorrect usage of “foreign_key” in migration script

* Use `ActiveModel::Errors#delete` instead of deprecated clear method

* Fix link headers tests on Rails 6.1

Rails 6.1 adds values to the Link header by default, thus it is not a
LinkHeader object anymore. Fix the test to parse the Link header instead
of assuming it is a LinkHeader.

* Prepare Mastodon for zeitwerk autoloader (Rails 6)

Add inflections and rename/move a few classes.

In particular, app/lib/exceptions.rb and app/lib/sanitize_config.rb
were manually loaded while still in autoload paths.

* Add inflection for Url → URL

* Fix misuse of foreign_type

* Fix use of removed "add_template_helper"

* Use response.media_type instead of response.content_type in tests

* Fix CSV export controller test on Rails 6

Rails 6 sets a "filename*" field in the Content-Disposition header to
explicitly encode the filename as UTF-8.

This changes checks the first part of the Content-Disposition header so
it matches in both Rails 5 and Rails 6.

* Fix emoji formatting with Rails 6

* Make emoji output more idiomatic and robust

* Switch from redis-rails gem to built-in Rails redis cache storage

The "ends_with?" method is just a Rails alias of Ruby's "end_with?" method.
Using the latter makes the code less brittle.

"headers" is provided by Rails, Rack can't rely on it

* Drop dependency on secure_headers, use always_write_cookie instead

* Fix cookies in Tor Hidden Services by moving configuration to application.rb

* Instead of setting always_write_cookie at boot, monkey-patch ActionDispatch