chore: clippy fixes

src_testbed/testbed.rs

@@ -1114,7 +1114,6 @@ fn update_testbed(
 ) {
     let meshes = &mut *meshes;
     let materials = &mut *materials;
-    let prev_example = state.selected_example;
 
     // Handle inputs
     {

src_testbed/ui.rs

@@ -10,7 +10,6 @@ use crate::testbed::{
 };
 
 use crate::PhysicsState;
-use bevy_egui::egui::WidgetType::CollapsingHeader;
 use bevy_egui::egui::{Slider, Ui};
 use bevy_egui::{egui, EguiContexts};
 use rapier::dynamics::IntegrationParameters;