TestRunner does not load Revit 2025 assemblies

#### Description:

When investigating [this check failure](https://github.com/BHoM/BHoM_Engine/pull/3491/checks?check_run_id=40403765856), I noticed that currently `TestRunner` fails to load any of the Revit 2025 assemblies due to framework incompatibility (it is built against .NET Framework 4.7.2, while Revit stuff is .NET 8). We had a brief chat with @IsakNaslundBh and speculated that we may have to upgrade the project to the latest framework version that we use in toolkits, but:
- although checks will start passing, issues may still persist (e.g. Rhino 6 will most likely still fail to load .NET Core assemblies)
- not sure how much of a Pandora's box will it open, I did an initial run after the upgrade and versioning seemed to stop working on a dozen of objects

Raising this issue to spin up the discussion - I do not think it is mission critical, but is definitely reducing the confidence in our code, would be good to action rather sooner than later.