Use default keyword argument in generated optional fields

[mjperrone]

Is your feature request related to a problem? Please describe.

The generator produces code that is not compatible with PEP 681's dataclass_transform interface. For more details see https://github.com/microsoft/pyright/issues/7166

Describe the solution you'd like I would like the generator to use the default= keyword argument instead of using the positional argument.

Describe alternatives you've considered

I can work around it by ignoring the pyright lint errors or by explicitly adding optional fields.

Additional context

Example spec:

type: object
properties:
  fieldWithNoDescription:
    type: string
  fieldWithDescription:
    type: string
    description: text describing the field

Produces:

from typing import Optional
from pydantic import BaseModel, Field

class ModelWithOptionalFields(BaseModel):
    fieldWithNoDescription: Optional[str] = None
    fieldWithDescription: Optional[str] = Field(
        None,
        description="Optional field with a default value of None and a description",
    )

But I would like it to produce:

from typing import Optional
from pydantic import BaseModel, Field

class ModelWithOptionalFields(BaseModel):
    fieldWithNoDescription: Optional[str] = None
    fieldWithDescription: Optional[str] = Field(
        default=None,
        description="Optional field with a default value of None and a description",
    )