Use TypeAlias where possible for type aliases (#7630)

stubs/aiofiles/aiofiles/os.pyi

@@ -3,10 +3,11 @@ from _typeshed import StrOrBytesPath
 from asyncio.events import AbstractEventLoop
 from os import stat_result
 from typing import Any, Sequence, overload
+from typing_extensions import TypeAlias
 
 from . import ospath as path
 
-_FdOrAnyPath = int | StrOrBytesPath
+_FdOrAnyPath: TypeAlias = int | StrOrBytesPath
 
 async def stat(
     path: _FdOrAnyPath,  # noqa: F811

stubs/aiofiles/aiofiles/threadpool/__init__.pyi

@@ -8,14 +8,14 @@ from _typeshed import (
 )
 from asyncio import AbstractEventLoop
 from typing import Any, Callable, overload
-from typing_extensions import Literal
+from typing_extensions import Literal, TypeAlias
 
 from ..base import AiofilesContextManager
 from .binary import AsyncBufferedIOBase, AsyncBufferedReader, AsyncFileIO, _UnknownAsyncBinaryIO
 from .text import AsyncTextIOWrapper
 
-_OpenFile = StrOrBytesPath | int
-_Opener = Callable[[str, int], int]
+_OpenFile: TypeAlias = StrOrBytesPath | int
+_Opener: TypeAlias = Callable[[str, int], int]
 
 # Text mode: always returns AsyncTextIOWrapper
 @overload