ci: migrate to GitHub Actions w/ matrix

.github/workflows/ci.yml

@@ -0,0 +1,35 @@
+name: CI
+on: [push]
+jobs:
+  ci:
+    name: CI - Node ${{ matrix.node-version }}, ${{ matrix.os }}
+
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        # TODO: add back Node 18 once node-canvas is properly supported: https://github.com/Automattic/node-canvas/issues/2025
+        node-version: [14.x, 16.x] # LTS Node: https://nodejs.org/en/about/releases/
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+
+    steps:
+    - name: Checkout repo
+      uses: actions/checkout@v3
+    - name: Setup Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v3
+      with:
+        node-version: ${{ matrix.node-version }}
+        cache: 'npm'
+    - name: Install
+      run: npm ci
+
+    - name: Typecheck
+      run: npm run tsc
+    - name: Lint
+      run: npm run lint
+    - name: Build
+      run: npm run build
+
+    - name: Test w/ coverage report
+      run: npm run test:coverage
+    - name: Upload coverage report to Codecov
+      uses: codecov/codecov-action@v2