Update MSRV to 1.80 (#5457)

Because some dependencies now require it, see:
* https://github.com/emilk/egui/pull/5456

crates/egui-wgpu/src/winit.rs

@@ -728,7 +728,7 @@ impl Painter {
             .retain(|id, _| active_viewports.contains(id));
     }
 
-    #[allow(clippy::unused_self)]
+    #[allow(clippy::needless_pass_by_ref_mut, clippy::unused_self)]
     pub fn destroy(&mut self) {
         // TODO(emilk): something here?
     }