fix: Support enums

[jefersondaniel]

I'm sending this PR as a draft because the tests don't pass yet. The JSON mode of pydantic also affects the datetime serialization so it creates a break compatibility.

[KozyrevIvan]

Perhaps we should exclude computed_field here

This can be done for example like this:

computed_fields = set(model.model_computed_fields)
data = model_with_id.model_dump(
    mode="json", 
    exclude=computed_fields,
 )

[jefersondaniel]

The main issue I see is storing a Date object in mongo and also supporting a Enum. Converting it to JSON would convert the Date type into a "string" because JSON don't have Date times, its part of BSON.