Apply cargo check fixes

src/breakout_plugin.rs

@@ -1,5 +1,4 @@
 use bevy::{
-    input::keyboard::Key,
     math::bounding::{Aabb2d, BoundingCircle, BoundingVolume, IntersectsVolume},
     prelude::*,
     sprite::MaterialMesh2dBundle,

src/main.rs

@@ -5,8 +5,6 @@ mod breakout_plugin;
 mod hello_world_plugin;
 
 use birdoids_plugin::BoidsPlugin;
-use breakout_plugin::BreakoutPlugin;
-use hello_world_plugin::HelloPlugin;
 
 fn main() {
     App::new()