fix superclass for UnixDatagramServer and UnixStreamServer (#11115)

Author: tungol

stdlib/socketserver.pyi

@@ -86,7 +86,7 @@ class UDPServer(TCPServer):
     def get_request(self) -> tuple[tuple[bytes, _socket], _RetAddress]: ...  # type: ignore[override]
 
 if sys.platform != "win32":
-    class UnixStreamServer(BaseServer):
+    class UnixStreamServer(TCPServer):
         server_address: _AfUnixAddress  # type: ignore[assignment]
         def __init__(
             self,
@@ -95,7 +95,7 @@ if sys.platform != "win32":
             bind_and_activate: bool = True,
         ) -> None: ...
 
-    class UnixDatagramServer(BaseServer):
+    class UnixDatagramServer(UDPServer):
         server_address: _AfUnixAddress  # type: ignore[assignment]
         def __init__(
             self,