Incorrect import path in SQLAlchemySession documentation

[Shahzain-Ali]

Description

The documentation currently shows an incorrect import path for SQLAlchemySession.

Current (incorrect) code

from agents.extensions.memory import SQLAlchemySession

Correct code

from agents.extensions.memory.sqlalchemy_session import SQLAlchemySession

Found on the official docs page:
(https://openai.github.io/openai-agents-python/sessions/sqlalchemy_session)

This small fix will help avoid ImportError for users following the documentation.

[seratch]

Both actually work runtime, but indeed importing from agents.extensions.memory.sqlalchemy_session might be developer-friendly (as the code editor provides a link to the module); if interested, your contribution would be appreciated

[habema]

The import actually works, but there is an issue with the static analysis of the exports from the memory extensions.

@seratch Fixing this issue uncovers a number of supressed mypy issues. I'll take a look at this and open a PR.