fix: scope github actions backup

avoid running this job in forked repo

Author: peterpeterparker

.github/workflows/backup.yml

@@ -16,6 +16,7 @@ jobs:
         with:
           service_account_key: ${{ secrets.FIRESTORE_BACKUP_TOKEN }}
           export_default_credentials: true
+        if: github.repository == 'deckgo/deckdeckgo'
       - run: gcloud info
       - run: gcloud config set project $PROJECT_ID
       - run: gcloud firestore export $BUCKET