Updated CHANGELOG.

Author: hpparvi

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to ExoIris will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.23.1] - 2025-12-18
+
+### Fixed
+- Fixed least-squares baseline fitting for transit models with NaNs.
+- Added "bspline-cubic" interpolation option as an alias for "bspline". The "bspline" option will be removed in a future 
+  release.
+
 ## [0.23.0] - 2025-12-16
 
 ### Changed