updated changelog

Author: adamrimon

CHANGELOG.md

@@ -16,6 +16,12 @@ should change the heading of the (upcoming) version to include a major version b
 
 -->
 
+# 6.4.2
+
+## @rjsf/utils
+
+- Fixed exponential slowdown with cross-referencing `oneOf`/`anyOf` definitions, fixing [#4990](https://github.com/rjsf-team/react-jsonschema-form/issues/4990)
+
 # 6.4.1
 
 ## Dev / docs / playground