exit if there are no changes

.github/workflows/examples_build_file_generation.yaml

@@ -26,6 +26,7 @@ jobs:
       - name: Update gazelle manifest
         working-directory: examples/build_file_generation
         run: |
+          if ! git diff --exit-code gazelle_python.yaml >/dev/null; exit 0; fi
           git config --global user.email "[email protected]"
           git config --global user.name "GH action"
           git add gazelle_python.yaml