avoid hourglass when performing the 15 minute refresh

src/app.rs

@@ -231,7 +231,6 @@ impl cosmic::Application for AppModel {
                 Task::none()
             }
             Message::RefreshWeather => {
-                self.is_loading = true;
                 Task::perform(fetch_weather(), |result| {
                     cosmic::Action::App(Message::WeatherUpdate(result))
                 })