ci: publish multi-arch images (amd64+arm64) with qemu

Author: Thomas Tupper

.github/workflows/publish-image.yml

@@ -39,6 +39,10 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
+      - name: Set up QEMU
+        if: steps.secrets.outputs.ready == 'true'
+        uses: docker/setup-qemu-action@v3
+
       - name: Set up Docker Buildx
         if: steps.secrets.outputs.ready == 'true'
         uses: docker/setup-buildx-action@v3
@@ -51,6 +55,7 @@ jobs:
         with:
           context: .
           push: true
+          platforms: linux/amd64,linux/arm64
           provenance: mode=max
           sbom: true
           tags: |