Update CHANGELOG

Author: ManifoldFR

CHANGELOG.md

@@ -6,6 +6,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+### Added
+- Added a second set of Python bindings based on nanobind ([#659](https://github.com/coal-library/coal/pull/659))
+
 ### Changed
 - Formatted all CMake listfiles using gersemi, add gersemi to pre-commit configuration ([#657](https://github.com/coal-library/coal/pull/657/files))