[Python] Avoid include own type (#8625)

This prevents the include of the type defined in the pyi,
otherwise this leads to error message like this:
error: Name XYZ already defined (possibly by an import)  [no-redef]

tests/MyGame/Example/NestedStruct.pyi

@@ -5,7 +5,6 @@ import numpy as np
 
 import flatbuffers
 import typing
-from MyGame.Example.NestedStruct import NestedStruct
 from MyGame.Example.TestEnum import TestEnum
 
 uoffset: typing.TypeAlias = flatbuffers.number_types.UOffsetTFlags.py_type