multiprocessing.reduction: improve recvfds and recv_handle (#8422)

Author: AlexWaygood

stdlib/multiprocessing/reduction.pyi

@@ -1,7 +1,9 @@
 import pickle
 import sys
+from _typeshed import HasFileno
 from abc import ABCMeta
 from copyreg import _DispatchTableType
+from socket import socket
 from typing import Any
 from typing_extensions import Literal
 
@@ -43,9 +45,9 @@ else:
     else:
         ACKNOWLEDGE: Literal[False]
 
-    def recvfds(sock, size): ...
+    def recvfds(sock: socket, size: int) -> list[int]: ...
     def send_handle(conn, handle, destination_pid) -> None: ...
-    def recv_handle(conn) -> None: ...
+    def recv_handle(conn: HasFileno) -> int: ...
     def sendfds(sock, fds) -> None: ...
     def DupFd(fd): ...