Add Codeberg as a supported git hosting service

[yaadata]

Thank you for an awesome tool. I wanted to add support for codeberg. Tested locally that opening pull-request works

PR Description

Codeberg is a Gitea-based git hosting service that uses the same URL patterns for pull requests and commits but differs on its hostname

Please check if the PR fulfills these requirements

• Cheatsheets are up-to-date (run go generate ./...)
• Code has been formatted (see here)
• Tests have been added/updated (see here for the integration test guide)
• Text is internationalised (see here)
• If a new UserConfig entry was added, make sure it can be hot-reloaded (see here)
• Docs have been updated if necessary
• You've read through your own file changes for silly mistakes etc

[stefanhaller]

Nice, thanks. I couldn't test this as I don't have a codeberg account myself, but I trust you that it works.

I pushed a fixup (1095bf0) to remove the changes from docs/; see #5010 for why we don't want these yet.