chore: fix the enum backfill action (#34182)

### Issue # (if applicable)

N/A

### Checklist
- [X] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: moelasmar

.github/workflows/enum-auto-updater.yml

@@ -114,7 +114,7 @@ jobs:
           gh pr create --title "chore(${moduleName#aws-}): add new enum values for ${moduleName#aws-}" \
            --body "This PR updates the enum values for ${moduleName#aws-}." \
            --base main \
-           --head "$branchName"
+           --head "$branchName" \
            --label "contribution/core,pr-linter/exempt-integ-test,pr-linter/exempt-readme,pr-linter/exempt-test"
           done
         env: