build(deps): update google-auth requirement in /samples/python/psycopg3 (#4215)

Updates the requirements on [google-auth](https://github.com/googleapis/google-auth-library-python) to permit the latest version.
- [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/commits)

---
updated-dependencies:
- dependency-name: google-auth
  dependency-version: 2.49.0
  dependency-type: direct:production
...

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samples/python/psycopg3/requirements.txt

@@ -2,4 +2,4 @@ psycopg[binary]~=3.3.3
 testcontainers~=4.14.1
 requests==2.32.5
 google~=3.0.0
-google.auth~=2.48.0
+google.auth~=2.49.0