Fix asyncio executor types (#13616)

Update type annotations for `run_in_executor` and `set_default_executor` in asyncio event loop interfaces to use more specific executor types from `concurrent.futures`

stdlib/asyncio/base_events.pyi

@@ -8,6 +8,7 @@ from asyncio.protocols import BaseProtocol
 from asyncio.tasks import Task
 from asyncio.transports import BaseTransport, DatagramTransport, ReadTransport, SubprocessTransport, Transport, WriteTransport
 from collections.abc import Callable, Iterable, Sequence
+from concurrent.futures import Executor, ThreadPoolExecutor
 from contextvars import Context
 from socket import AddressFamily, SocketKind, _Address, _RetAddress, socket
 from typing import IO, Any, Literal, TypeVar, overload
@@ -96,8 +97,8 @@ class BaseEventLoop(AbstractEventLoop):
     def call_soon_threadsafe(
         self, callback: Callable[[Unpack[_Ts]], object], *args: Unpack[_Ts], context: Context | None = None
     ) -> Handle: ...
-    def run_in_executor(self, executor: Any, func: Callable[[Unpack[_Ts]], _T], *args: Unpack[_Ts]) -> Future[_T]: ...
-    def set_default_executor(self, executor: Any) -> None: ...
+    def run_in_executor(self, executor: Executor | None, func: Callable[[Unpack[_Ts]], _T], *args: Unpack[_Ts]) -> Future[_T]: ...
+    def set_default_executor(self, executor: ThreadPoolExecutor) -> None: ...  # type: ignore[override]
     # Network I/O methods returning Futures.
     async def getaddrinfo(
         self,

stdlib/asyncio/events.pyi

@@ -9,6 +9,7 @@ from _asyncio import (
 from _typeshed import FileDescriptorLike, ReadableBuffer, StrPath, Unused, WriteableBuffer
 from abc import ABCMeta, abstractmethod
 from collections.abc import Callable, Sequence
+from concurrent.futures import Executor
 from contextvars import Context
 from socket import AddressFamily, SocketKind, _Address, _RetAddress, socket
 from typing import IO, Any, Literal, Protocol, TypeVar, overload
@@ -188,9 +189,9 @@ class AbstractEventLoop:
         def call_soon_threadsafe(self, callback: Callable[[Unpack[_Ts]], object], *args: Unpack[_Ts]) -> Handle: ...
 
     @abstractmethod
-    def run_in_executor(self, executor: Any, func: Callable[[Unpack[_Ts]], _T], *args: Unpack[_Ts]) -> Future[_T]: ...
+    def run_in_executor(self, executor: Executor | None, func: Callable[[Unpack[_Ts]], _T], *args: Unpack[_Ts]) -> Future[_T]: ...
     @abstractmethod
-    def set_default_executor(self, executor: Any) -> None: ...
+    def set_default_executor(self, executor: Executor) -> None: ...
     # Network I/O methods returning Futures.
     @abstractmethod
     async def getaddrinfo(