[codex] Update network troubleshooting peer checks - #763

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: DavidAnson/markdownlint-cli2-action@07035fd053f7be764496c0f8d8f9f41f98305101. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/