Updated CHANGELOG to include changes for 7.5.1-3

CHANGELOG

@@ -45,8 +45,15 @@ v 7.6.0
   - Possibility to create Milestones or Labels when Issues are disabled
   - Fix bug with showing gpg signature in tag
+v 7.5.3
+  - Bump gitlab_git to 7.0.0.rc12 (includes Rugged 0.21.2)
+
 v 7.5.2
   - Don't log Sidekiq arguments by default
+  - Fix restore of wiki repositories from backups
+
+v 7.5.1
+  - Add missing timestamps to 'members' table
 v 7.5.0
   - API: Add support for Hipchat (Kevin Houdebert)