deps: bump undici from 8.11.2 to 8.12.4 in /docs (#2395)

Bumps [undici](https://github.com/nodejs/undici) from 8.11.2 to 8.12.4.
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v8.11.2...v8.12.4)

---
updated-dependencies:
- dependency-name: undici
  dependency-version: 8.12.4
  dependency-type: indirect
...

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Co-authored-by: Brady Gaster <41929050+bradygaster@users.noreply.github.com>

Author: dependabot[bot]