chore(.github): Update update_contributors.yml

增加判断，让该 action 在 fork 的项目中不触发

.github/workflows/update_contributors.yml

@@ -13,6 +13,8 @@ jobs:
   contrib-readme-job:
     runs-on: ubuntu-latest
     name: A job to automate contributors in readme
+    # Only run workflow if the repository is not a fork
+    if: ${{ !github.event.repository.fork }}
     permissions:
       contents: write
       pull-requests: write