fix: bump undici from 7.25.0 to 7.28.0 in /packages/bigframes/tests/js

Bumps [undici](https://github.com/nodejs/undici) from 7.25.0 to 7.28.0.
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v7.25.0...v7.28.0)

---
updated-dependencies:
- dependency-name: undici
  dependency-version: 7.28.0
  dependency-type: indirect
...

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Author: dependabot[bot]