docs: drop GH pages build back to Node 16 for "digital envelope routines::unsupported" error

Author: mdeanjones

.github/workflows/gh-pages.yml

@@ -16,6 +16,8 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - uses: volta-cli/action@v3
+        with:
+          node-version: 16.9.0
       - name: Build
         run: |
           npm ci --no-audit