ci: use node v16 for Verify Files (#15364)

* ci: use node `v16`

* ci: keep using node v12 for browser test

We're still using Node 12 to build the site (including demo)

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     - uses: actions/checkout@v2
     - uses: actions/setup-node@v2
       with:
-        node-version: '14.x'
+        node-version: '16.x'
     - name: Install Packages
       run: npm install
     - name: Lint Files