Merge upstream changes

Bumps [sidekiq](https://github.com/mperham/sidekiq) from 5.2.6 to 5.2.7.
- [Release notes](https://github.com/mperham/sidekiq/releases)
- [Changelog](https://github.com/mperham/sidekiq/blob/master/Changes.md)
- [Commits](https://github.com/mperham/sidekiq/compare/v5.2.6...v5.2.7)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [capybara](https://github.com/teamcapybara/capybara) from 3.17.0 to 3.18.0.
- [Release notes](https://github.com/teamcapybara/capybara/releases)
- [Changelog](https://github.com/teamcapybara/capybara/blob/master/History.md)
- [Commits](https://github.com/teamcapybara/capybara/compare/3.17.0...3.18.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Fix #10616

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.10.2 to 1.10.3. **This update includes security fixes.**
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sparklemotion/nokogiri/compare/v1.10.2...v1.10.3)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [capybara](https://github.com/teamcapybara/capybara) from 3.16.2 to 3.17.0.
- [Release notes](https://github.com/teamcapybara/capybara/releases)
- [Changelog](https://github.com/teamcapybara/capybara/blob/master/History.md)
- [Commits](https://github.com/teamcapybara/capybara/compare/3.16.2...3.17.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Fixes #933

Due to glitch-soc's theming system, JS and CSS files are imported in a slightly
different order, and custom CSS rules were loaded *before* everything else.

They will now be loaded *after* everything else, which is a bit different from
upstream but should work better overall.

Support abbr, del, pre, blockquote, code, strong, b, em, i, and h1…h5
HTML elements in remote statuses, add corresponding CSS.

Merge upstream changes

Port d763d39d26 to glitch-soc

Conflicts:
- app/javascript/mastodon/features/compose/components/compose_form.js
  Upstream cleaned up a bit, including on lines in which
  we replaced the hardcoded 500 character limit with a maxChar
  constant. Applied the changes while keeping maxChar instead of 500.
- app/javascript/packs/public.js
  Moved upstream's new animated avatar hover handling in
  app/javascript/core/public.js
- app/javascript/styles/fonts/montserrat.scss
  Upstream fixed local font name, applied those changes.
- app/javascript/styles/fonts/roboto.scss
  Upstream fixed local font name, applied those changes.
- lib/mastodon/version.rb
  Upstream made repo URL configurable, did the same, but
  default to glitch-soc

Regression: only one warning at a time