update branches where sync script runs (#7401)

Author: jeff-allen-mongo

.github/workflows/repo-sync.yml

@@ -1,6 +1,13 @@
 name: Repo Sync
 
-on: push
+on:
+  push:
+    branches:
+      - master
+      - v7.2
+      - v7.0
+      - v6.0
+      - v5.0
 
 permissions:
   contents: write