Fix version tags in changelog

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project does **not** adhere to [Semantic Versioning](https://semver.org
 
 -   Queries for the current number of patients and the current treatment progress won't be answered by the treat patients behavior if there is no leader of the requested simulated region.
 -   The frontend for the treat patients behavior hides the "assigned personnel" column not only in the `unknown` but also the `noTreatment` phase.
+-   The diff link in the changelog for v0.4.0 now refers to the correct tags.
 
 ## [0.5.0] - 2023-05-08
 
@@ -200,10 +201,10 @@ and this project does **not** adhere to [Semantic Versioning](https://semver.org
 
 ### Initial unstable release of Digitale FüSim MANV
 
-[Unreleased]: https://github.com/hpi-sam/digital-fuesim-manv/compare/0.5.1...HEAD
-[0.5.1]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.5.0...0.5.1
+[Unreleased]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.5.1...HEAD
+[0.5.1]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.5.0...v0.5.1
 [0.5.0]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.4.0...v0.5.0
-[0.4.0]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.3.0...0.4.0
+[0.4.0]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.3.0...v0.4.0
 [0.3.0]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.2.1...v0.3.0
 [0.2.1]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.2.0...v0.2.1
 [0.2.0]: https://github.com/hpi-sam/digital-fuesim-manv/compare/v0.1.0...v0.2.0