add changelog entry

Author: blegat

Changelog.md

@@ -5,6 +5,12 @@ All notable Changes to the Julia package `Manopt.jl` will be documented in this
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+* add `Manopt.JuMP_Optimizer` implementing JuMP's solver interface
+
 ## [0.4.41] - 02/11/2023
 
 ### Changed
@@ -370,4 +376,4 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * the problem now contains a
 * `AbstractManoptSolverState` replaces `Options`
 * `random_point(M)` is replaced by `rand(M)` from `ManifoldsBase.jl
-* `random_tangent(M, p)` is replaced by `rand(M; vector_at=p)`
+* `random_tangent(M, p)` is replaced by `rand(M; vector_at=p)`