Updated CHANGELOG

Author: ekcoh

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -26,6 +26,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed icon scaling in Input Actions window.
 - Fixed an issue where removing the InputSystem package could lead to invalid input handling settings.
 - Fixed `ArgumentOutOfRangeException` when adding a new Control Scheme with any Device selected. [ISXB-1129](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1129)
+- Fixed a CS0105 compiler warning due to duplicate using statement in test source code (ISXB-1247).
 
 ### Changed
 - Added back the InputManager to InputSystem project-wide asset migration code with performance improvement (ISX-2086).