update workflow node version

Author: mskian

.github/workflows/buildtest.yml

@@ -13,7 +13,7 @@ jobs:
     - uses: actions/[email protected]
     - uses: actions/[email protected]
       with:
-         node-version: '14.x'
+         node-version: '16.x'
     - name: use node
       run: |
        npm install