chore: clear typehinting errors

dzgui/controllers/mc.py

@@ -544,7 +544,7 @@ class Controller(GObject.GObject):
     def get_client_name(self) -> str:
         # NOTE: only possible values are "Steam" and "Flatpak"
         cmd = self.query_config(Preferences.CLIENT)
-        return cmd.split()[0].capitalize()
+        return str(cmd.split()[0].capitalize())
 
     def present_window(self) -> None:
         self.mediator.window.present_with_time(Gdk.CURRENT_TIME)