Update CHANGELOG (general changes)

Author: ManifoldFR

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [gar] Throw an exception if trying to instantiate `ParallelRiccatiSolver` with num_threads smaller than 2.
 - [API BREAKING] Rename friction cone for centroidal into CentroidalFrictionCone ([#234](https://github.com/Simple-Robotics/aligator/pull/234))
 - [gar] Rework `RiccatiSolverDense` to not use inner struct `FactorData`
+- Various changes to `gar` tests and `test_util`, add `LQRKnot::isApprox()`
 
 ### Removed