Add GitHub Actions workflow to test changes (#40)

.github/workflows/test.yml

@@ -0,0 +1,21 @@
+name: Test
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: Setup node
+        uses: actions/setup-node@v2.5.1
+        with:
+          node-version: 16
+          cache: 'yarn'
+      - run: yarn install
+      - run: yarn run test