DOC: Update changelog for release

CHANGELOG.md

@@ -5,25 +5,13 @@ All notable changes to this project 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).
 
-## [Unreleased] ##
-
-### Added ###
-
-### Changed ###
-
-### Deprecated ###
-
-### Removed ###
+## [0.9.1]  - 2024-09-26 ##
 
 ### Fixed ###
 
 * ImpossibleMergeErrors now correctly include the problematic property
   and its values in their string representation.
 
-### Security ###
-
-### Documentation ###
-
 ## [0.9.0] - 2024-09-05 ##
 
 ### Added ###