refactor: use elif in AsyncClient._handle_event()

src/dumdum/client/async_client.py

@@ -136,7 +136,7 @@ def _handle_event(self, event: ClientEvent) -> None:
         if isinstance(event, ClientEventIncompatibleVersion):
             assert self._writer is not None
             self._writer.close()
-        if isinstance(event, ClientEventAuthentication):
+        elif isinstance(event, ClientEventAuthentication):
             self._set_authentication(event.success)
         self._dispatch_event(event)