False positive `Explicit export is not defined` for item backed by `__getattr__`

**Description of the false positive**

The `__all__` array includes a string which is handled by `def __getattr__(name: str):`, but CodeQL complains:

**Code samples or links to source code**

https://github.com/check-spelling-sandbox/adk-python/blob/79db5168aefdf658a36b4833809602c819c3740b/src/google/adk/tools/retrieval/__init__.py#L19

https://github.com/check-spelling-sandbox/adk-python/blob/79db5168aefdf658a36b4833809602c819c3740b/src/google/adk/tools/retrieval/__init__.py#L25-L30

**URL to the alert on GitHub code scanning (optional)**

https://github.com/check-spelling-sandbox/adk-python/security/quality/rules/py%2Fundefined-export

Sorry, there doesn't appear to be a standard url for it

Read the linked Python __init__.py sample and inspect the py/undefined-export rule that reports the alert. Trace how the rule handles __all__ and __getattr__, then use the CodeQL query tests to reproduce the case. Done means a valid export supplied through __getattr__ is no longer reported as undefined.

Rédigé par le modèle d'indexation à partir du texte de l'issue.