Security release 2.5.2

Release checklist

• Bump version in mix.exs
• Compile a changelog
• Create an MR with an announcement to pleroma.social: pleroma.social!80 (merged)

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) !3863 (merged)