Update CHANGELOG.md

Author: ank1m

CHANGELOG.md

@@ -6,6 +6,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- update grouping algorithm to use day in US Central as the first part of unique grouping identifier ([#177](https://github.com/nasa/batchee/pull/177))([**@ank1m**](https://github.com/ank1m))
+
 ## [1.3.0] - 2024-11-19
 
 ### Changed