ci: setup github actions

.github/workflows/ci.yml

@@ -0,0 +1,18 @@
+name: Build/test
+on:
+  push:
+    branches:
+      - "**"
+  pull_request:
+    branches:
+      - master
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: 20
+      - run: npm install
+      - run: npm test