use _typeshed's Path aliases (#4214)

stdlib/3/asyncio/base_tasks.pyi

@@ -1,16 +1,8 @@
-
-import sys
-
-from typing import List, Optional, Union
+from _typeshed import AnyPath
+from typing import List, Optional
 from types import FrameType
 from . import tasks
 
-if sys.version_info >= (3, 6):
-    from builtins import _PathLike
-    _PathType = Union[bytes, str, _PathLike]
-else:
-    _PathType = Union[bytes, str]
-
 def _task_repr_info(task: tasks.Task) -> List[str]: ...  # undocumented
 def _task_get_stack(task: tasks.Task, limit: Optional[int]) -> List[FrameType]: ...  # undocumented
-def _task_print_stack(task: tasks.Task, limit: Optional[int], file: _PathType): ...  # undocumented
+def _task_print_stack(task: tasks.Task, limit: Optional[int], file: AnyPath): ...  # undocumented

stdlib/3/asyncio/proactor_events.pyi

@@ -1,20 +1,9 @@
-import sys
 from socket import socket
-from typing import Any, Mapping, Optional, Union
+from typing import Any, Mapping, Optional
+from typing_extensions import Literal
 
 from . import base_events, constants, events, futures, streams, transports
 
-if sys.version_info >= (3, 7):
-    from os import PathLike
-    _Path = Union[str, PathLike[str]]
-else:
-    _Path = str
-
-if sys.version_info >= (3, 8):
-    from typing import Literal
-else:
-    from typing_extensions import Literal
-
 class _ProactorBasePipeTransport(transports._FlowControlMixin, transports.BaseTransport):
 
     def __init__(self, loop: events.AbstractEventLoop, sock: socket, protocol: streams.StreamReaderProtocol, waiter: Optional[futures.Future[Any]] = ..., extra: Optional[Mapping[Any, Any]] = ..., server: Optional[events.AbstractServer] = ...) -> None: ...

stdlib/3/asyncio/selector_events.pyi

@@ -1,15 +1,7 @@
 import selectors
-import sys
-from socket import socket
-from typing import Any, Optional, Union
+from typing import Optional
 
-from . import base_events, events
-
-if sys.version_info >= (3, 7):
-    from os import PathLike
-    _Path = Union[str, PathLike[str]]
-else:
-    _Path = str
+from . import base_events
 
 class BaseSelectorEventLoop(base_events.BaseEventLoop):
     def __init__(self, selector: Optional[selectors.BaseSelector] = ...) -> None: ...