Enhancement: Support attrs converters

Description

Attrs has an attribute conversion feature where a function can be provided to be run whenever the attribute value is set.

https://www.attrs.org/en/stable/examples.html#conversion

This is not being run when the post request body is an attrs class. Looking for clarity on if this is by design or a fix if not. Also, is there another preferred pattern in litestar to do this type of payload attribute conversion?

URL to code causing the issue

No response

MCVE

requirements.txt

litestar[standard,attrs]==2.10.0

api.py

from __future__ import annotations

import attrs
from litestar import (
    Litestar,
    post,
)

@attrs.define
class TestRequestPayload:
    a: str = attrs.field(converter=str.lower)
    b: str = attrs.field(converter=str.lower)

@post("/test1")
async def test1(data: TestRequestPayload) -> dict:
    return attrs.asdict(data)

@post("/test2")
async def test2(data: TestRequestPayload) -> dict:
    # Naked evolve basically re-instantiates the object causing the converters to be run
    return attrs.asdict(attrs.evolve(data))

app = Litestar(
    route_handlers=[test1, test2],
)

Steps to reproduce

litestar --app api:app run

Make a request to the test1 route, note data response unchanged from input

$ curl --request POST localhost:8000/test1 --data '{"a": "Hello", "b": "World"}' ; echo
{"a":"Hello","b":"World"}

Make a request to the test2 route, note data response lowercased relative to input

$ curl --request POST localhost:8000/test2 --data '{"a": "Hello", "b": "World"}' ; echo
{"a":"hello","b":"world"}

Screenshots

No response

Logs

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Litestar Version

2.10.0

Platform

[X] Linux
[ ] Mac
[ ] Windows
[ ] Other (Please specify in the description above)

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litestar-org / litestar