CHANGELOG.md: add entry for version 2.4.0

Author: lucas-baran

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [2.4.0] - 2025-05-09
+### Added
+- Add utility functions for the inspector:
+  - InspectorUtils.SetIndentScope: use EditorGUI.IndentScope to set the editor GUI indent level
+  - InspectorUtils.DrawHelpbox: draw a helpbox with the specified message and severity at given position
+- Add RectExtensions class: provides extensions functions for Rect
+
 ## [2.3.2] - 2025-04-18
 ### Updated
 - Update SubAssetPicker drawer to display mixed values and disable picker when multiple objects with different values are selected