chore: Add GitHub CI config

Author: robtarr

.circleci/config.yml

@@ -0,0 +1,11 @@
+name: CI
+on: ['push']
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: test
+        run: |
+          npm ci
+          npm run test