build(deps): bump undici from 6.2.1 to 6.6.1

Bumps [undici](https://github.com/nodejs/undici) from 6.2.1 to 6.6.1.
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v6.2.1...v6.6.1)

---
updated-dependencies:
- dependency-name: undici
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>