Add permissions in update-scheduled-release-version.yml

.github/workflows/update-scheduled-release-version.yml

@@ -3,6 +3,9 @@ name: Update Scheduled Release Version
 on:
   workflow_dispatch: # Manual trigger only. Triggered by release-scheduler.yml on main.
 
+permissions:
+  contents: read
+
 jobs:
   update-scheduled-release-version:
     name: Update Scheduled Release Version