ci: add typecheck action

Author: ariser

.github/workflows/ci.yml

@@ -14,3 +14,13 @@ jobs:
       - uses: actions/setup-node@v2
       - run: npm ci
       - run: npx commitlint --from ${{ github.event.pull_request.base.sha }} --to ${{ github.event.pull_request.head.sha }} --verbose
+
+  typecheck:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-node@v2
+      - run: npm ci
+      - run: npm run typecheck