chore: setup simple unit-tests workflow

.github/workflows/unit-tests.yml

@@ -0,0 +1,21 @@
+name: Unit Tests
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: 10.x
+    - name: yarn install, build, and test
+      run: |
+        npm install -g yarn
+        yarn install
+        yarn bundle
+        yarn test