ci(test): move to GitHub Actions

Author: gr2m

.github/workflows/test.yml

@@ -0,0 +1,22 @@
+name: Test
+on:
+  push:
+    branches:
+      - "greenkeeper/**"
+  pull_request:
+    types: [opened, synchronize]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node_version: [8, 10, 12]
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node_version }}
+      - run: npm ci
+      - run: npm test