chore: removed old Flipper asset

lib/game/game_assets.dart

@@ -10,7 +10,6 @@ extension PinballGameAssetsX on PinballGame {
       images.load(components.Assets.images.ball.keyName),
       images.load(components.Assets.images.flipper.left.keyName),
       images.load(components.Assets.images.flipper.right.keyName),
-      images.load(Assets.images.components.flipper.path),
       images.load(Assets.images.components.background.path),
       images.load(Assets.images.components.spaceship.androidTop.path),
       images.load(Assets.images.components.spaceship.androidBottom.path),

lib/gen/assets.gen.dart

@@ -21,10 +21,6 @@ class $AssetsImagesComponentsGen {
   AssetGenImage get background =>
       const AssetGenImage('assets/images/components/background.png');
 
-  /// File path: assets/images/components/flipper.png
-  AssetGenImage get flipper =>
-      const AssetGenImage('assets/images/components/flipper.png');
-
   $AssetsImagesComponentsSpaceshipGen get spaceship =>
       const $AssetsImagesComponentsSpaceshipGen();
 }