Build images for arm64

Signed-off-by: Stephen Finucane <stephen@that.guru>

Author: stephenfin

.github/workflows/publish-image.yaml

@@ -24,6 +24,8 @@ jobs:
         uses: docker/setup-qemu-action@v3
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
+        with:
+          platforms: linux/amd64,linux/arm64
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
         with: