build matrix

.github/workflows/test.yaml

@@ -9,6 +9,9 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        arch: ["linux/amd64", "linux/arm64"]
     steps:
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v1
@@ -20,7 +23,7 @@ jobs:
         id: docker_build
         uses: docker/build-push-action@v2
         with:
-          platforms: linux/amd64,linux/arm64
+          platforms: ${{ matrix.arch }}
           push: false
   test:
     runs-on: ubuntu-latest