Remove unused ExitRequested pyotherside event

src/backend/pyotherside_events.py

@@ -29,13 +29,6 @@ class PyOtherSideEvent:
         pyotherside.send(type(self).__name__, *args)
 
 
-@dataclass
-class ExitRequested(PyOtherSideEvent):
-    """Request for the application to exit."""
-
-    exit_code: int = 0
-
-
 @dataclass
 class NotificationRequested(PyOtherSideEvent):
     """Request a notification and window manager alert to be shown.