chore(gh-actions): add simple test

.github/workflows/run-test.yml

@@ -0,0 +1,26 @@
+name: run-test
+
+on: push
+
+jobs:
+  # general test run
+  test:
+
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+        node-version: [8.x, 10.x, 12.x, 14.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: git submodule update --recursive --init
+    - run: npm install
+    - run: npm install ext/protagonist
+    - run: npm test