use current node-version 16 (#5587)

.github/workflows/fpb-lint.yml

@@ -12,7 +12,7 @@ jobs:
     - name: Use Node.js
       uses: actions/setup-node@v1
       with:
-        node-version: '14.x'
+        node-version: '16.x'
     - run: npm install -g free-programming-books-lint
     - run: fpb-lint ./books/
     - run: fpb-lint ./casts/