also build docker when testing

.github/workflows/test.yaml

@@ -7,6 +7,21 @@ on:
   pull_request:
 
 jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+        with:
+          install: true
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          platforms: linux/amd64,linux/arm64
+          push: false
   test:
     runs-on: ubuntu-latest
     services: