bpo-45192: Fix a bug that infers the type of an os.PathLike[bytes] object as str (GH-28323)

An object implementing the os.PathLike protocol can represent a file
system path as a str or bytes object.
Therefore, _infer_return_type function should infer os.PathLike[str]
object as str type and os.PathLike[bytes] object as bytes type.