Bump google-auth from 2.5.0 to 2.6.0 (#111)

Bumps [google-auth](https://github.com/googleapis/google-auth-library-python) from 2.5.0 to 2.6.0.
- [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@v2.5.0...v2.6.0)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -3,7 +3,7 @@ certifi==2021.10.8
 charset-normalizer==2.0.11
 gbq==0.4.0
 google-api-core==2.4.0
-google-auth==2.5.0
+google-auth==2.6.0
 google-cloud-bigquery==2.32.0
 google-cloud-core==2.2.2
 google-crc32c==1.3.0