Add Github Action to run tests

Author: thgh

.github/workflows/test.yaml

@@ -0,0 +1,21 @@
+name: Node.js CI
+on:
+  push:
+    branches: [ v3, v4 ]
+  pull_request:
+    branches: [ v3, v4 ]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [10.x, 12.x, 14.x, 15.x]
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: yarn --frozen-lockfile
+    - run: yarn build
+    - run: yarn test