0.6.0

Usning marshmallow instead of pydantic, becase pydantic is incorrectly works with json schema. If model's filed is optional, in pydantic it must me defined as None default, but if field is None default, in nested schemas for openapi, schemas is equal to null, instead of nested model. Pydantic have more inconvinient moment in my opinion, but with this json schema reason, it is critical reason