Merge branch 'sh-fix-changelog' into 'master'

Remove duplicate CHANGELOG entry

mail_room was bumped for 8.12.5.

See merge request !6806

CHANGELOG

@@ -2,7 +2,6 @@ Please view this file on the master branch, on stable branches it's out of date.
 v 8.13.0 (unreleased)
   - Truncate long labels with ellipsis in labels page
-  - Bump mail_room to v0.8.1 to fix thread cleanup issue
   - Update runner version only when updating contacted_at
   - Add link from system note to compare with previous version
   - Improve issue load time performance by avoiding ORDER BY in find_by call