Fix the typing hints for Python 3.6+

Thankfully the supported version is 3.7+, so this should be fine. I'm
not sure I understand why typing sometimes fails on the CI env, but
this should likely fix it.

Author: iustin

posix1e.pyi

@@ -3,7 +3,7 @@
 # NOTE: This dynamically typed stub was automatically generated by stubgen.
 
 from typing import Optional, Union, Tuple, TypeVar
-from builtins import _PathLike as PathLike
+from os import PathLike
 
 from typing import overload
 ACL_DUPLICATE_ERROR: int