release: Update CHANGELOG.md for 3.1.0

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+## [3.1.0] - 2024-07-04
+
 ### Fixed
 
 - Fix `appendModel` when joints after the base are in parallel ([#2295](https://github.com/stack-of-tasks/pinocchio/pull/2295))
@@ -988,7 +990,8 @@ The model can either be parsed from a URDF format or be created by appendending
         • Fixed (concatenation of two consecutive bodies)
 
 
-[Unreleased]: https://github.com/stack-of-tasks/pinocchio/compare/v3.0.0...HEAD
+[Unreleased]: https://github.com/stack-of-tasks/pinocchio/compare/v3.1.0...HEAD
+[3.1.0]: https://github.com/stack-of-tasks/pinocchio/compare/v3.0.0...v3.1.0
 [3.0.0]: https://github.com/stack-of-tasks/pinocchio/compare/v2.7.1...v3.0.0
 [2.7.1]: https://github.com/stack-of-tasks/pinocchio/compare/v2.7.0...v2.7.1
 [2.7.0]: https://github.com/stack-of-tasks/pinocchio/compare/v2.6.21...v2.7.0