Add CI test for node 16

Author: keichi

.github/workflows/nodejs.yml

@@ -16,12 +16,12 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [10.x, 12.x, 14.x]
+        node-version: [10, 12, 14, 16]
 
     steps:
     - uses: actions/checkout@v2
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v2
       with:
         node-version: ${{ matrix.node-version }}
     - run: npm ci