chore: upgrade gh action to node 16

.github/workflows/unit.yml

@@ -12,7 +12,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
         with:
-          node-version: '14.x'
+          node-version: '16.x'
       - name: Install dependencies
         run: npm ci
       - name: Run unit tests