Update CHANGELOG-EE.md for 12.1.12-ee

[ci skip]

CHANGELOG-EE.md

@@ -456,6 +456,16 @@ Please view this file on the master branch, on stable branches it's out of date.
 - Fix alignment of activity dropdown in epic tabs; add counter to discussion tab.
 
 
+## 12.1.12
+
+### Security (4 changes)
+
+- Hide approvers if a rule has any hidden groups.
+- Fix Gitaly SearchBlobs flag RPC injection [Gitaly v1.53.4].
+- Prevent IDOR when adding groups to protected environments.
+- Upgrade mermaid to prevent XSS.
+
+
 ## 12.1.10
 
 - No changes.