ci: add GitHub Actions workflow 'Test'

.github/workflows/Test.yml

@@ -0,0 +1,20 @@
+name: Test
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+env:
+  CI: true
+  DOCKER_BUILDKIT: 1
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+
+    - uses: actions/checkout@v2
+
+    - run: ./build-all.sh