Fix whitespace

.github/workflows/docker-gcr.yml

@@ -63,8 +63,10 @@ jobs:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           message: |
             I pushed these containers:
+            
             - `gcr.io/tensorflow-sigs/build:${{ github.event.number }}-python3.9`
             - `gcr.io/tensorflow-sigs/build:${{ github.event.number }}-python3.8`
             - `gcr.io/tensorflow-sigs/build:${{ github.event.number }}-python3.7`
+            
             Re-apply the `build and push to gcr.io for staging` label to
             rebuild and push again. This comment will only be posted once.