Make enums inherit from str and enum.Enum in ModelGenerator.render

[alxdrcirilo]

Is your feature request related to a problem? Please describe.
Generating Python classes from an avro schema using dataclasses-avroschema.ModelGenerator.render method with the model_type argument set to ModelType.AVRODANTIC will render a Python class with the enum.

For example:

class SomeEnum(enum.Enum):
    ...

Describe the solution you'd like
Since enums in avro are always strings, it would be nice to have the aforementioned method render.

If we take the previous example:

class SomeEnum(str, enum.Enum):
    ...

Describe alternatives you've considered
NA

Additional context
NA

[marcosschroh]

Yes, it makes sense. We should do it regardless the ModelType that is used.