ci: bump node 12 to node 16

Author: evanw

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Setup Node.js environment
         uses: actions/[email protected]
         with:
-          node-version: 12
+          node-version: 16
 
       - name: Checkout code
         uses: actions/checkout@v2