Prevent an XSS vector in the add approver email

ee/app/views/notify/add_merge_request_approver_email.html.haml

@@ -2,7 +2,7 @@
   %div
     #{link_to @updated_by.name, user_url(@updated_by)} added you as an approver for:
 %p.details
-  != merge_path_description(@merge_request, '→')
+  = merge_path_description(@merge_request, '→')
 
 - if @merge_request.assignees.any?
   %p

ee/changelogs/unreleased/security-fix-email-xss-master.yml

+---
+title: Prevent an XSS vector in the add approver email
+merge_request:
+author:
+type: security