chore(deps): bump undici in /sample/33-graphql-mercurius

Bumps [undici](https://github.com/nodejs/undici) from 5.6.1 to 5.8.0.
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v5.6.1...v5.8.0)

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

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