add docker build

.github/workflows/build.yaml

@@ -0,0 +1,22 @@
+name: build
+
+on:
+  push:
+    branches:
+      - "docker-test"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+        with:
+          platforms: arm, arm64
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          push: true
+          tags: ghcr.io/knifa/led-matrix-zmq-server:edge