Update changelog with version 7.7.2

CHANGELOG

@@ -63,6 +63,10 @@ v 7.8.0
   - 
   - Added support for firing system hooks on group create/destroy and adding/removing users to group (Boyan Tabakov)
+v 7.7.2
+  - Update GitLab Shell to version 2.4.2 that fixes a bug when developers can push to protected branch
+  - Fix issue when LDAP user can't login with existing GitLab account
+
 v 7.7.1
   - Improve mention autocomplete performance
   - Show setup instructions for GitHub import if disabled