Update CHANGELOG

Author: ManifoldFR

CHANGELOG.md

@@ -19,6 +19,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Fixed
 - Use the right table to store `configure-args` cmeel argument ([#403](https://github.com/Simple-Robotics/proxsuite/pull/403))
 - Allow project to be used as an external CMake project (FetchContent) ([#408](https://github.com/Simple-Robotics/proxsuite/pull/408))
+- Fix -Wdeprecated-literal-operator warning ([#420](https://github.com/Simple-Robotics/proxsuite/pull/420))
 
 ### Removed
 - Don't release PyPy package on GNU/Linux anymore ([#403](https://github.com/Simple-Robotics/proxsuite/pull/403))