AudioTransforms are dropped when saving MixedCuts?

[m-wiesner]

Perhaps this wasn't the intended usage of MixedCuts, but it seems that if you mix cuts to which audio transforms have been applied and then try to save the mixed cuts, the transform types (names) are dropped when they are transform objects instead of dictionaries.

In MonoCuts there doesn't seem to be a problem. I assume that this is because the transforms are saved in the Cuts that are stored in the MixedCut tracks and not in the transform field of the MixedTrack, which makes sense because each track could have different transforms applied to it, but I think it is causing a problem with serialization.

Specifically, when the object gets passed to the dataclasses asdict function, it doesn't seem to store the type of transform when the transform is specified as an AudioTransform object. It just stores the fields.

[pzelasko]

I forgot that mixed cut also has a transforms field now. We’ll need to add test coverage for this too. Do you have some time to fix? Otherwise I’ll do it but probably only after the next week.

[pzelasko]

Check #1370 for the fix