Turn @config into a dataclass_transform (#31541)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

vllm/config/model.py

@@ -9,7 +9,6 @@ from typing import TYPE_CHECKING, Any, Literal, cast, get_args
 
 import torch
 from pydantic import ConfigDict, Field, field_validator, model_validator
-from pydantic.dataclasses import dataclass
 
 import vllm.envs as envs
 from vllm.config.model_arch import (
@@ -97,8 +96,7 @@ AttnTypeStr = Literal[
 ]
 
 
-@config
-@dataclass(config=ConfigDict(arbitrary_types_allowed=True))
+@config(config=ConfigDict(arbitrary_types_allowed=True))
 class ModelConfig:
     """Configuration for the model."""