chore: run workflow with node 16.x (instead of 15.x)

Author: kioviensis

.github/workflows/default.yaml

@@ -14,7 +14,7 @@ jobs:
       - uses: actions/setup-node@v2
         name: 'Setup node'
         with:
-          node-version: '15.x'
+          node-version: '16.x'
 
       - name: 'Install npm dependencies'
         run: yarn install