Invalid type hint for CharEnumField in generated migration script

[kinnay]

Describe the bug
If I generate a migration file with tortoise migrate for a model that contains a CharEnumField, and then run mypy on my project, it produces an error. The reason seems to be that CharEnumField does not return an instance of Field.

When the migration creates a new table (ops.CreateModel) the following error is printed:

error: List item 1 has incompatible type "tuple[str, ExampleEnum]"; expected "tuple[str, Field[Any] | ManyToManyRelation[Any] | None]"  [list-item]

When the migration adds a CharEnumField to an existing table, the following error is printed:

error: Argument "field" to "AddField" has incompatible type "ExampleEnum"; expected "Field[Any] | ManyToManyRelation[Any] | None"  [arg-type]

To Reproduce
Below is a minimal reproducible example.

models.py:

from tortoise.fields import CharEnumField
from tortoise.models import Model

import enum


class ExampleEnum(enum.StrEnum):
    Value1 = enum.auto()
    Value2 = enum.auto()


class ExampleModel(Model):
    field: ExampleEnum = CharEnumField(ExampleEnum)

config.json:

{
    "connections": {
        "default": "sqlite://:memory:"
    },
    "apps": {
        "monitor": {
            "models": ["models"],
            "migrations": "migrations",
            "default_connection": "default"
        }
    }
}

Steps to reproduce:

1. tortoise --config-file config.json makemigrations
2. mypy migrations

Expected behavior
No mypy errors on scripts that are generated by Tortoise.