Bump undici from 5.26.3 to 5.28.3 in /website

Bumps [undici](https://github.com/nodejs/undici) from 5.26.3 to 5.28.3.
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v5.26.3...v5.28.3)

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

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