Release v5.0.4

Changed

• The native runner documentation now describes what happens when a Microsoft.Testing.Platform session is stopped. Running specification classes finish their cleanup once, queued classes do not start, and the platform does not deliver results after a hard cancellation. (part of #77)

Fixed

• The experimental native runner now reports a cancelled Establish, Because or Destroy the same way whether the specification uses generated or reflection-based lifecycle calls. Both raise SpecificationCancelledException with the phase and the original exception. (part of #77)