Update changelog for version 4.2.3

Updated changelog for version 4.2.3 with fixes, changes, and additions.

Author: nfriedly

changelog.md

@@ -6,6 +6,20 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [v4.2.3](https://github.com/express-rate-limit/rate-limit-redis/releases/tag/v4.2.2)
+
+### Fixed 
+
+- Properly fixed the race condition that v4.2.1 attempted to address
+
+### Changed
+
+- Minimum redis version is now 2.6.12, up from 2.6.0 previously
+
+### Added
+
+- Documented minimum redis version in readme
+
 ## [v4.2.2](https://github.com/express-rate-limit/rate-limit-redis/releases/tag/v4.2.2)
 
 ### Fixed