chore: update CHANGELOG for Neptune Scale logger support

Author: SiddhantSadangi

src/lightning/pytorch/CHANGELOG.md

@@ -27,6 +27,15 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 -
 
 
+---
+
+## [unreleased] - 2025-03-31
+
+### Added
+
+- Add support for Neptune Scale logger ([#20686](https://github.com/Lightning-AI/pytorch-lightning/pull/20686))
+
+
 ---
 
 ## [2.5.1] - 2025-03-18