build(deps): bump google-auth from 2.30.0 to 2.31.0 in /tests (garden…

…linux#2188)

Bumps [google-auth](https://github.com/googleapis/google-auth-library-python) from 2.30.0 to 2.31.0.
- [Release notes](https://github.com/googleapis/google-auth-library-python/releases)
- [Changelog](https://github.com/googleapis/google-auth-library-python/blob/main/CHANGELOG.md)
- [Commits](googleapis/google-auth-library-python@v2.30.0...v2.31.0)

---
updated-dependencies:
- dependency-name: google-auth
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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