use _typeshed's Path aliases (#4214)

stdlib/3/imp.pyi

@@ -1,7 +1,6 @@
-# Stubs for imp (Python 3.6)
-
 import os
 import sys
+from _typeshed import StrPath
 import types
 from typing import Any, IO, List, Optional, Tuple, TypeVar, Union
 
@@ -13,11 +12,6 @@ from _imp import create_dynamic as create_dynamic
 
 _T = TypeVar('_T')
 
-if sys.version_info >= (3, 6):
-    _Path = Union[str, os.PathLike[str]]
-else:
-    _Path = str
-
 SEARCH_ERROR: int
 PY_SOURCE: int
 PY_COMPILED: int
@@ -32,21 +26,21 @@ IMP_HOOK: int
 def new_module(name: str) -> types.ModuleType: ...
 def get_magic() -> bytes: ...
 def get_tag() -> str: ...
-def cache_from_source(path: _Path, debug_override: Optional[bool] = ...) -> str: ...
-def source_from_cache(path: _Path) -> str: ...
+def cache_from_source(path: StrPath, debug_override: Optional[bool] = ...) -> str: ...
+def source_from_cache(path: StrPath) -> str: ...
 def get_suffixes() -> List[Tuple[str, str, int]]: ...
 
 class NullImporter:
-    def __init__(self, path: _Path) -> None: ...
+    def __init__(self, path: StrPath) -> None: ...
     def find_module(self, fullname: Any) -> None: ...
 
 # PathLike doesn't work for the pathname argument here
 def load_source(name: str, pathname: str, file: Optional[IO[Any]] = ...) -> types.ModuleType: ...
 def load_compiled(name: str, pathname: str, file: Optional[IO[Any]] = ...) -> types.ModuleType: ...
-def load_package(name: str, path: _Path) -> types.ModuleType: ...
+def load_package(name: str, path: StrPath) -> types.ModuleType: ...
 def load_module(name: str, file: IO[Any], filename: str, details: Tuple[str, str, int]) -> types.ModuleType: ...
 if sys.version_info >= (3, 6):
-    def find_module(name: str, path: Union[None, List[str], List[os.PathLike[str]], List[_Path]] = ...) -> Tuple[IO[Any], str, Tuple[str, str, int]]: ...
+    def find_module(name: str, path: Union[None, List[str], List[os.PathLike[str]], List[StrPath]] = ...) -> Tuple[IO[Any], str, Tuple[str, str, int]]: ...
 else:
     def find_module(name: str, path: Optional[List[str]] = ...) -> Tuple[IO[Any], str, Tuple[str, str, int]]: ...
 def reload(module: types.ModuleType) -> types.ModuleType: ...