update changelog

Author: ytdHuang

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased](https://github.com/qutip/QuantumToolbox.jl/tree/main)
 
 - Introduce new methods of `sesolve_map` and `mesolve_map` for advanced usage. Users can now customize their own `iter`ator structure, `prob_func` and `output_func`. ([#565])
+- Simplify type structure for time evolution solutions. ([#572])
 
 ## [v0.37.0]
 Release date: 2025-10-12
@@ -339,3 +340,4 @@ Release date: 2024-11-13
 [#555]: https://github.com/qutip/QuantumToolbox.jl/issues/555
 [#557]: https://github.com/qutip/QuantumToolbox.jl/issues/557
 [#565]: https://github.com/qutip/QuantumToolbox.jl/issues/565
+[#572]: https://github.com/qutip/QuantumToolbox.jl/issues/572