winrt/client: fix logger.warn deprecation warning

When run with python3.10 -dev X, we get a warning that warn is
deprecated and we should replace it with warning.

bleak/backends/winrt/client.py

@@ -256,7 +256,7 @@ async def connect(self, **kwargs) -> bool:
 
         def handle_services_changed():
             if not self._services_changed_events:
-                logger.warn("%s: unhandled services changed event", self.address)
+                logger.warning("%s: unhandled services changed event", self.address)
             else:
                 for event in self._services_changed_events:
                     event.set()