add ARM build

.github/workflows/build.yml

@@ -24,6 +24,8 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v1
+        with:
+          platforms: linux/amd64,linux/arm64
 
       - name: Cache Docker layers
         uses: actions/cache@v2
@@ -37,6 +39,7 @@ jobs:
         with:
           context: .
           push: true
+          platforms: linux/amd64,linux/arm64
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=local,src=/tmp/.buildx-cache