ci: build multi-arch image

.github/workflows/docker-image.yml

@@ -11,6 +11,11 @@ jobs:
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
+    - name: Set up Docker Buildx
+      id: buildx
+      uses: docker/setup-buildx-action@v3
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v3
     - name: Login to Docker Hub
       uses: docker/login-action@v2.1.0
       with:
@@ -21,4 +26,5 @@ jobs:
       with:
         context: .
         push: true
+        platforms: linux/amd64,linux/arm64,linux/arm/v7
         tags: cyfershepard/jellystat:latest