fix(deps): bump google-auth from 2.38.0 to 2.39.0

Bumps [google-auth](https://github.com/googleapis/google-auth-library-python) from 2.38.0 to 2.39.0.
- [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](https://github.com/googleapis/google-auth-library-python/compare/v2.38.0...v2.39.0)

---
updated-dependencies:
- dependency-name: google-auth
  dependency-version: 2.39.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -12,7 +12,7 @@ djangorestframework==3.16.0
 firebase-admin==6.7.0
 google-api-core==2.24.2
 google-api-python-client==2.166.0
-google-auth==2.38.0
+google-auth==2.39.0
 google-auth-httplib2==0.2.0
 google-cloud-core==2.4.3
 google-cloud-firestore==2.20.1