bpo-45192: Fix a bug that infers the type of an os.PathLike[bytes] object as str (GH-28323) (GH-29111)

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.
(cherry picked from commit 6270d3eeaf17b50abc4f8f4d97790d66179638e4)

Co-authored-by: Kyungmin Lee <rekyungmin@gmail.com>