adds linting build step

.github/workflows/lint.yml

@@ -0,0 +1,21 @@
+name: lint
+
+on:
+  push:
+    branches: [v4.x]
+  pull_request:
+    branches: [v4.x]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Use Node.js
+        uses: actions/setup-node@v1
+        with:
+          node-version: '16.x'
+      - name: Install dependencies
+        run: yarn
+      - run: yarn lint