Add GitHub Action to run CI tests (#162)

.github/workflows/build-test.yml

@@ -0,0 +1,21 @@
+name: build-test
+
+on:
+  push:
+    branches: ["master"]
+  pull_request:
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Setup node
+        uses: actions/setup-node@v2
+        with:
+          node-version: 14
+      - name: Install dependencies
+        run: yarn --frozen-lockfile
+      - name: Run tests
+        run: yarn test