Update changelog

Author: nisheethlahoti

src/lightning/fabric/CHANGELOG.md

@@ -144,6 +144,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 ### Fixed
 
+- Fixed issue where DDP subprocesses that used Hydra would set hydra's working directory to current directory ([#18145](https://github.com/Lightning-AI/lightning/pull/18145))
+
+
 - Fixed issue where running on TPUs would select the wrong device index ([#17227](https://github.com/Lightning-AI/lightning/pull/17227))