Update CI workflow.

Author: trekhleb

.github/workflows/CI.yml

@@ -0,0 +1,35 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [ 14.x ]
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Setup Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install dependencies
+        run: npm i
+
+      - name: Run linting
+        run: npm run lint
+
+      - name: Run tests
+        run: npm run coverage
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v1