Add github CI worklfow

.github/workflows/ci.yaml

@@ -0,0 +1,28 @@
+name: Test
+on:
+  - push
+  - pull_request
+
+jobs:
+  build:
+    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        node: [ '12', '14', '16' ]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Use Node.js ${{ matrix.node }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node }}
+
+      - name: Fetch submodules
+        run: git submodule update --init
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run test suite
+        run: npm run test