Create token for the proper repository (#714)

(cherry picked from commit fc68314)

Co-authored-by: Nick Cao <nickcao@nichi.co>

Author: jumpstarter-backport-bot[bot]

.github/workflows/trigger-packages-index.yaml

@@ -27,6 +27,9 @@ jobs:
         with:
           app-id: ${{ secrets.JUMPSTARTER_BACKPORT_BOT_APP_ID }}
           private-key: ${{ secrets.JUMPSTARTER_BACKPORT_BOT_PRIVATE_KEY }}
+          owner: ${{ github.repository_owner }}
+          repositories: |
+            packages
 
       - name: Trigger packages repository index generation
         uses: peter-evans/repository-dispatch@v3