update what's new

dist/preview release/what's new.md

@@ -57,3 +57,4 @@
 ## Breaking changes
 - `Gamepads` was removed in favor of `scene.gamepadManager`
 - `DynamicFloatArray`, `MapTexture` and `RectPakingMap` were removed because there were not used anymore
+- `IAssetTask` was removed in favor of `AbstractAssetTask` class