Fix changelog for Manopt 0.5.4 release

Changelog.md

@@ -5,19 +5,14 @@ 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).
 
-## [0.5.5] - unreleased
-
-### Added
-
-* icons upfront external links when they link to another package or wikipedia.
-
-## [0.5.4] - November 27, 2024
+## [0.5.4] - December 11, 2024
 
 ### Added
 
 * An automated detection whether the tutorials are present
    if not an also no quarto run is done, an automated `--exlcude-tutorials` option is added.
 * Support for ManifoldDiff 0.4
+* icons upfront external links when they link to another package or wikipedia.
 
 ## [0.5.3] – October 18, 2024