🧪 Use base_ref @ PR base sanity check

Author: webknjaz

.github/workflows/reusable-smoke-test.yml

@@ -35,8 +35,11 @@ jobs:
     steps:
     - name: Fail on PRs against illegal branches
       if: >-
-        github.event_name == 'pull_request'
-        && github.ref_name == github.event.repository.default_branch
+        github.event_name == 'pull_request' &&
+        github.base_ref == format(
+            'refs/heads/{0}',
+            github.event.repository.default_branch
+        )
       run: exit 1
 
   fail-fast: