Bump google-auth from 2.6.3 to 2.6.6

Bumps [google-auth](https://github.com/googleapis/google-auth-library-python) from 2.6.3 to 2.6.6.
- [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/v2.6.3...v2.6.6)

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

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

requirements.txt

@@ -12,7 +12,7 @@ django-compat==1.0.15
 django-cors-headers==3.11.0
 django-db-logger==0.1.11
 djangorestframework==3.13.1
-google-auth==2.6.3
+google-auth==2.6.6
 gunicorn==20.1.0
 idna==3.3
 importlib-metadata==4.11.3