add arm64 builds again

.gitea/workflows/ci.yml

@@ -89,6 +89,8 @@ jobs:
             org.opencontainers.image.description=teufa container image
             org.opencontainers.image.source=https://brosner.dev/brosner/teufa
             org.opencontainers.image.licenses=MIT
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
       - name: Setup docker buildx
         uses: docker/setup-buildx-action@v3
       - name: Build image
@@ -99,5 +101,5 @@ jobs:
           labels: ${{ steps.meta.outputs.labels }}
           annotations: ${{ steps.meta.outputs.annotations }}
           target: prod
-          platforms: linux/amd64
+          platforms: linux/amd64,linux/arm64
           push: true