Add TODO comment for Stainless generator override issue

Document that the type ignore comment in _typing.py will be overwritten
by Stainless generator. This needs to be addressed either by updating
the Stainless config or moving the utility to lib/

Author: prassanna-ravishankar

src/agentex/_utils/_typing.py

@@ -53,6 +53,8 @@ def is_typevar(typ: type) -> bool:
 
 _TYPE_ALIAS_TYPES: tuple[type[typing_extensions.TypeAliasType], ...] = (typing_extensions.TypeAliasType,)
 if sys.version_info >= (3, 12):
+    # NOTE: This type ignore will be overwritten by Stainless generator.
+    # TODO: Update Stainless config to include this type ignore or move to lib/
     _TYPE_ALIAS_TYPES = (*_TYPE_ALIAS_TYPES, typing.TypeAliasType)  # type: ignore[assignment]