Add a GH actions linux build

Author: pimterry

.github/workflows/ci.yml

@@ -0,0 +1,16 @@
+name: CI
+on: push
+jobs:
+  build:
+    name: Build & test
+    runs-on: ubuntu-latest
+    container: httptoolkit/act-build-base
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 14
+
+      - run: npm ci
+      - run: npm build