Fix workflow syntax

Issue gh-14535

.github/workflows/trigger-dependabot-auto-merge-forward.yml

@@ -3,7 +3,7 @@ name: Trigger Dependabot Auto Merge Forward
 on:
   push:
     branches:
-      - [5-9]+.[5-9]+.x
+      - '[5-9]+.[5-9]+.x'
 
 permissions: read-all