update docker image platforms

Author: TimothyYe

.github/workflows/docker-image.yml

@@ -26,5 +26,6 @@ jobs:
       - name: Build and push the docker image
         uses: docker/build-push-action@v2
         with:
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
           push: true
           tags: timothyye/godns:latest,timothyye/godns:${{steps.tag.outputs.tag}}