Update default runtime to node16 (#192)

.github/workflows/check-dist.yml

@@ -23,10 +23,10 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Set Node.js 12.x
+      - name: Set Node.js 16.x
         uses: actions/setup-node@v2
         with:
-          node-version: 12.x
+          node-version: 16.x
 
       - name: Install dependencies
         run: npm ci