Add build artifact verification step

Add verification step for build artifact before deployment.

.github/workflows/deploy-gce.yml

@@ -46,6 +46,9 @@ jobs:
       - name: 'Set up Cloud SDK'
         uses: 'google-github-actions/setup-gcloud@v2'
         
+      - name: Verify build artifact
+        run: ls -lh ${{ steps.binary.outputs.path }}
+
       - name: 'Deploy binary to GCE'
         run: |
           # Ensure ~/.local/bin exists