* Migrate to go modules

* make vendor

* Update mvdan.cc/xurls

* make vendor

* Update code.gitea.io/git

* make fmt-check

* Update github.com/go-sql-driver/mysql

* make vendor

* Replace linkRegex with xurls library

Rather than maintaining a complicated regex to match URLs for
autolinking, gitea can use this existing go library that takes care of
the matching with very little code change to gitea itself. After
spending a while trying to find the perfect regex for all cases this library
still works better as it is more flexible than a single regex ever will be.

This will also fix the following issues: #5844 #3095 #3381

This passes all our current tests and I've added new ones mentioned in
those issues as well.

* Use xurls.StrictMatchingScheme instead of xurls.Strict

This is much faster and we only care about https? links to preserve
existing behavior.