release: 2.5.1

Release checklist

• Bump version in mix.exs
• Compile a changelog
• Create an MR with an announcement to pleroma.social pleroma.social!78 (merged)
• pleroma/secteam/pleroma!29

post-merge

• Tag the release on the merge commit
• Make the tag into a Gitlab Release™
• Merge stable into develop (in case the fixes are already in develop, use git merge -s ours --no-commit and manually merge the changelogs)