Add GitHub Actions to run tests (#164)

.github/workflows/main.yml

@@ -0,0 +1,30 @@
+name: Node CI
+
+on: [push]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [8, 10, 12, 14, 16]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node-version }}
+      - name: Cache modules
+        uses: actions/cache@v2
+        with:
+          path: ~/.npm
+          key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-node-
+      - name: Install dependencies
+        run: |
+          npm ci
+      - name: npm test
+        run: npm test