ci: enhance GitHub Actions workflow to include label condition for fixture regeneration

Author: ryan-gang

.github/workflows/fixtures.yml

@@ -11,6 +11,7 @@ on:
 
 jobs:
   regenerate_fixtures:
-    if: github.event.label == 'regenerate-fixtures'
     uses: codecrafters-io/tester-utils/.github/workflows/fixtures.yml@fixture-gen-action
-    secrets: inherit
+    secrets: inherit
+    with:
+      label: 'regenerate-fixtures'