refresh_from_db doesn't update the initial state

[partizaans]

Hi! When calling refresh_from_db() on a model instance, the values are reloaded from the database. However, the _initial_state stored on a LifeCycleModel instance is not recalculated. If the maintainers consider this a bug, I can provide a fix by overriding the refresh_from_db method in the library Mixin.

[EnriqueSoria]

That makes sense to me