Use relative time for update_checked in detail view

src/ui/detail_view.rs

@@ -634,7 +634,7 @@ fn build_overview_tab(record: &AppImageRecord, db: &Rc<Database>) -> gtk::Box {
     if let Some(ref checked) = record.update_checked {
         let row = adw::ActionRow::builder()
             .title("Last checked")
-            .subtitle(checked)
+            .subtitle(&widgets::relative_time(checked))
             .build();
         updates_group.add(&row);
     }