update github actions workflow

.github/workflows/ci.yaml

@@ -52,7 +52,7 @@ jobs:
         id: set-output
         run: |
           echo "GHA_DOCKER_PUSH_IMAGE_TAG=`date +%Y-%m-%dT%H-%M`" >> $GITHUB_ENV
-          echo "::set-output name=GHA_DOCKER_PUSH_IMAGE_TAG::${{ env.GHA_DOCKER_PUSH_IMAGE_TAG }"
+          echo "::set-output name=GHA_DOCKER_PUSH_IMAGE_TAG::${{ env.GHA_DOCKER_PUSH_IMAGE_TAG }}"
       - name: Build container image with Jib, push to container repo
         run: |
           mvn --batch-mode compile com.google.cloud.tools:jib-maven-plugin:build -Djib.to.tags=latest,${{ env.GHA_DOCKER_PUSH_IMAGE_TAG }}