build also on arm64

.github/workflows/ci_docker.yml

@@ -44,6 +44,7 @@ jobs:
         uses: docker/build-push-action@v2
         with:
           # relative path to the place where source code with Dockerfile is located
+          platforms: linux/amd64,linux/arm64
           context: .
           file: Dockerfile_no_qr_reader
           # Note: tags has to be all lower-case
@@ -57,6 +58,7 @@ jobs:
       - name: "qr_reader: Build image and push to Docker Hub and GitHub Container Registry"
         uses: docker/build-push-action@v2
         with:
+          platforms: linux/amd64,linux/arm64
           # relative path to the place where source code with Dockerfile is located
           context: .
           # Note: tags has to be all lower-case