Prepare changelog for v3.27.0

Author: paulbalandan

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this library will be documented in this file:
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [v3.27.0](https://github.com/NexusPHP/cs-config/compare/v3.26.4...v3.27.0) - 2025-12-12
+
+- Add `preserve_existing_declaration` option to `declare_strict_types`
+- update to php-cs-fixer v3.92
+- Add support for rule customisation policies
+
 ## [v3.26.4](https://github.com/NexusPHP/cs-config/compare/v3.26.3...v3.26.4) - 2025-09-27
 
 - Add but disable `phpdoc_tag_no_named_arguments`