Build multi-platform docker image

.github/workflows/docker.yml

@@ -3,7 +3,7 @@ name: docker
 on:
   push:
     branches:
-      - master
+      - '*'
     tags:
       - '*'
 
@@ -30,10 +30,13 @@ jobs:
       env:
         REPOSITORY: '${{ github.repository }}'
 
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v1
+
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v1
 
-    - name: Login to Github registry
+    - name: Log in to Github registry
       uses: docker/login-action@v1
       with:
         username: ${{ github.actor }}
@@ -42,7 +45,8 @@ jobs:
 
     - uses: docker/build-push-action@v2
       with:
-        push: true
+        platforms: linux/amd64,linux/arm64
+        push: false # TODO: true
         tags: ghcr.io/${{ env.REPOSITORY_LC }}:${{ env.DOCKER_TAG }}
 
   build_5_5:
@@ -79,6 +83,6 @@ jobs:
     
     - uses: docker/build-push-action@v2
       with:
-        push: true
+        push: false # TODO: true
         file: Dockerfile@swift-5.5
         tags: ghcr.io/${{ env.REPOSITORY_LC }}:5.5-${{ env.DOCKER_TAG }}