fix: use back port toekn (#1231)

.github/workflows/backport.yml

@@ -34,7 +34,7 @@ jobs:
         name: Create backport pull requests
         uses: korthout/backport-action@v3
         with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
+          github_token: ${{ secrets.BACKPORT_TOKEN }}
 
   open-issue:
     permissions: