Enable multi-arch Docker builds

Author: ChrispyBacon-dev

.github/workflows/docker-publish.yml

@@ -21,6 +21,9 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
@@ -49,6 +52,8 @@ jobs:
           context: .
           file: Dockerfile
           push: ${{ github.event_name != 'pull_request' }}
+          load: ${{ github.event_name == 'pull_request' }}
+          platforms: ${{ github.event_name == 'pull_request' && 'linux/amd64' || 'linux/amd64,linux/arm64' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=gha