Update docker.yml

.github/workflows/docker.yml

@@ -31,6 +31,11 @@ jobs:
         run: |
           echo "${DOCKER_PASSWORD}" | docker login --username "${DOCKER_USERNAME}" --password-stdin
 
+      - name: Docker buildx image and push on master branch
+      if: github.ref == 'refs/heads/master'
+      run: |
+        docker buildx build --output "type=image,push=true" --platform=linux/amd64,linux/arm/v7,linux/arm64 --tag xjasonlyu/tun2socks:latest .
+
       - name: Replace tag without `v`
         if: startsWith(github.ref, 'refs/tags/')
         uses: actions/github-script@v3