update changelog

Author: matthiasgeihs

packages/keyring-controller/CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Upgrade mock encryptor to support multiple ciphertexts ([#5943](https://github.com/MetaMask/core/pull/5943))
+
+
 ## [22.0.1]
 
 ### Changed