Make the change range more precise

Author: frostming

.github/workflows/sync.yaml

@@ -43,7 +43,7 @@ jobs:
         run: |
           pip install pre-commit
           pre-commit run --all-files pofmt
-          git add .
+          git add docs/ src/
           git commit -m "Update po files by GitHub Actions"
 
       - name: Push changes