update changelog

Author: fabinsch

CHANGELOG.md

@@ -6,6 +6,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+### What's Changed
+* Switch from self-hosted runner for macos-14-ARM to runner from github ([#306](https://github.com/Simple-Robotics/proxsuite/pull/306))
+
 ## [0.6.4] - 2024-03-01
 
 ### What's Changed