Update to node 16 (#689)

* Update to node 16

* update setup-node version

* Update check-dist.yml

update setup node version

* update dist/index.js

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
     steps:
       - uses: actions/setup-node@v1
         with:
-          node-version: 12.x
+          node-version: 16.x
       - uses: actions/checkout@v2
       - run: npm ci
       - run: npm run build