tools: bump undici from 6.28.0 to 6.29.1 in /tools/doc

Bumps [undici](https://github.com/nodejs/undici) from 6.28.0 to 6.29.1.
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v6.28.0...v6.29.1)

---
updated-dependencies:
- dependency-name: undici
  dependency-version: 6.29.1
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]