chore: use app-slug instead of app-id for token generation

Author: notgitika

.github/workflows/sync-preview.yml

@@ -21,7 +21,7 @@ jobs:
         id: app-token
         uses: actions/create-github-app-token@v1
         with:
-          app-id: ${{ secrets.APP_ID }}
+          app-slug: agentcore-devx-automation
           private-key: ${{ secrets.APP_PRIVATE_KEY }}
 
       - name: Checkout preview