chore: Update to Rust version 1.85.0 (#1860)

This is a small step toward fixing #1727

examples/apps/canvas/src/main.rs

@@ -117,7 +117,7 @@ impl App {
         }
     }
 
-    fn cycle_marker(&mut self) {
+    const fn cycle_marker(&mut self) {
         self.marker = match self.marker {
             Marker::Dot => Marker::Braille,
             Marker::Braille => Marker::Block,

examples/apps/chart/src/main.rs

@@ -128,7 +128,7 @@ impl App {
                 format!("{}", self.window[0]),
                 Style::default().add_modifier(Modifier::BOLD),
             ),
-            Span::raw(format!("{}", (self.window[0] + self.window[1]) / 2.0)),
+            Span::raw(format!("{}", f64::midpoint(self.window[0], self.window[1]))),
             Span::styled(
                 format!("{}", self.window[1]),
                 Style::default().add_modifier(Modifier::BOLD),

examples/apps/scrollbar/src/main.rs

@@ -60,24 +60,24 @@ impl App {
         }
     }
 
-    fn scroll_down(&mut self) {
+    const fn scroll_down(&mut self) {
         self.vertical_scroll = self.vertical_scroll.saturating_add(1);
         self.vertical_scroll_state = self.vertical_scroll_state.position(self.vertical_scroll);
     }
 
-    fn scroll_up(&mut self) {
+    const fn scroll_up(&mut self) {
         self.vertical_scroll = self.vertical_scroll.saturating_sub(1);
         self.vertical_scroll_state = self.vertical_scroll_state.position(self.vertical_scroll);
     }
 
-    fn scroll_left(&mut self) {
+    const fn scroll_left(&mut self) {
         self.horizontal_scroll = self.horizontal_scroll.saturating_sub(1);
         self.horizontal_scroll_state = self
             .horizontal_scroll_state
             .position(self.horizontal_scroll);
     }
 
-    fn scroll_right(&mut self) {
+    const fn scroll_right(&mut self) {
         self.horizontal_scroll = self.horizontal_scroll.saturating_add(1);
         self.horizontal_scroll_state = self
             .horizontal_scroll_state