Bug: default_factory with PydanticDTO

[FranzForstmayr]

Description

Using PydanticDTO with a datetime field and default_factory does not work anymore since #3721.
The get request returns Bad Request

URL to code causing the issue

No response

MCVE

from datetime import datetime

import pydantic as pydantic_v2

from litestar import  post
from litestar.contrib.pydantic.pydantic_dto_factory import PydanticDTO
from litestar.testing import create_test_client


def test_pydanticdto_with_default_factory() -> None:
    _now = datetime.fromisoformat("2024-01-01T12:42:42")

    class User(pydantic_v2.BaseModel):
        timestamp: datetime = pydantic_v2.Field(default_factory=lambda: _now)

    @post("/", dto=PydanticDTO[User])
    async def create_user(data: User) -> User:
        return data

    with create_test_client(create_user) as client:
        response = client.post("/", json={})
        assert response.status_code == 201
        assert User.model_validate(response.json()) == User.model_validate({})

test_pydanticdto_with_default_factory()

Steps to reproduce

Execute the code above.

Litestar Version

2.12.0

Platform

• Linux
• Mac
• Windows
• Other (Please specify in the description above)

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