add git diff command

Author: realDuYuanChao

.github/workflows/checkstyle.yml

@@ -20,6 +20,7 @@ jobs:
       - name: Commit Format changes
         if: failure()
         run: |
+          git diff
           git config --global user.name github-actions
           git config --global user.email '${GITHUB_ACTOR}@users.noreply.github.com'
           git remote set-url origin https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/$GITHUB_REPOSITORY