remove more unwrap

src/pages/repetitions.rs

@@ -450,7 +450,7 @@ impl RepetitionsState {
 
                     let date = (*now)
                         .checked_sub_days(Days::new(30 * 7 - i * 7 - j - 1))
-                        .unwrap();
+                        .unwrap_or_default();
 
                     column = column.push(tooltip(
                         iced::widget::container(space().height(15).width(15)).style(