Update Dymola version for unit testing

[lucasverleyen]

Dymola 2022x is used to simulate the unit tests on the server (blizz) and locally, as described in the readme: https://github.com/open-ideas/IDEAS/blob/master/IDEAS/Resources/Scripts/tests/README.md. This issue is to update the Dymola version to 2024x and to update the readme accordingly.

[jelgerjansen]

Dymola released their new version (2025x) on December 12th. I propose we immediately switch to this version (similar to the IBPSA library).