Update build_test.yaml manifest generation

Author: ayufan

.github/workflows/build_test.yaml

@@ -117,7 +117,7 @@ jobs:
         username: ${{ secrets.DOCKERHUB_TEST_USERNAME }}
         password: ${{ secrets.DOCKERHUB_TEST_TOKEN }}
     - name: Run dockerhub-manifest
-      run: ./release.bash "${{ env.REGISTRY }}:${{ env.TAG }}"
+      run: ./release.bash "${{ env.REGISTRY }}:${{ env.TAG }}" manifest
     - name: Comment image name on PR
       if: github.event_name == 'pull_request'
       env: