chore(deps): update mkdocs requirement from >=1.6 to >=1.6.1 in /docs - #9

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: rustsec/audit-check@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/