Derive default as now required by clippy (#376)

- [x] Changelog updated / no changelog update needed

examples/the-hat-chooses-the-wizard/src/enemies.rs

@@ -21,18 +21,14 @@ enum UpdateState {
     Remove,
 }
 
+#[derive(Default)]
 pub enum Enemy<'a> {
     Slime(Slime<'a>),
     Snail(Snail<'a>),
+    #[default]
     Empty,
 }
 
-impl<'a> Default for Enemy<'a> {
-    fn default() -> Self {
-        Enemy::Empty
-    }
-}
-
 pub enum EnemyUpdateState {
     None,
     KillPlayer,