Add buildx to fix imageid/digest issue

As per docker/build-push-action#579

.github/workflows/workflow.yaml

@@ -17,6 +17,11 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
     - uses: actions/checkout@v2
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v1
+      with:
+        version: v0.8.2
 
     - name: Log in to container  registry
       uses: docker/login-action@v1