Add changelog item

[ci skip]

Author: nfourtythree

CHANGELOG.md

@@ -3,7 +3,8 @@
 ## Unreleased
 
 - Fixed a bug where newly created variants weren’t visible on Edit product screens. 
-- Fixed a SQL error that could occur when viewing product indexes. 
+- Fixed a SQL error that could occur when viewing product indexes.
+- Fixed a PHP error that occurred when applying project config changes after updating. ([#4185](https://github.com/craftcms/commerce/issues/4185))
 
 ## 5.5.0.1 - 2025-11-24