This PR adds client identification to Redis connections created by Flask-Session, allowing Redis operators to see which library is connecting to their servers.

Redis servers support the lib_name and lib_version parameters (introduced in redis-py) to help operators identify which upstream libraries are connecting. This improves observability and debugging for Redis operators.

Following redis-py best practices, lib_name and lib_version identify the upstream library (Flask-Session) rather than redis-py itself.

Implementation

• Added get_flask_session_version() utility function to retrieve the Flask-Session version using importlib.metadata with fallback to __version__
• Added get_redis_py_version() utility function to retrieve the redis-py version
• Added add_redis_version_info() utility function to set lib_name="redis-py(flask-session_v<version>)" and lib_version=<redis-py-version>
• Updated RedisSessionInterface.__init__() to call add_redis_version_info()
• Only sets these parameters if not already provided by the user, ensuring user-provided values are never overridden

ReadTheDocs Configuration Fix

This PR also fixes the missing Sphinx configuration in .readthedocs.yaml that was causing all documentation builds to fail:

• Added configuration: docs/conf.py to the sphinx section
• This key is now required by ReadTheDocs (see their blog post)
• This fix unblocks documentation builds for this PR and all future contributions

Testing

• Added unit tests in tests/test_redis.py to verify version identification behavior
• Tests verify that custom lib_name and lib_version values are respected and not overridden
• All existing tests pass

Checklist:

• Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• Add an entry in CHANGES.rst summarizing the change and linking to the issue.
• Run pytest and tox, no tests failed.