[misc] error early for old-style class (#10304)

Signed-off-by: youkaichao <youkaichao@gmail.com>

vllm/model_executor/models/llava.py

@@ -259,7 +259,7 @@ def init_vision_tower_for_llava(
 @INPUT_REGISTRY.register_input_processor(input_processor_for_llava)
 class LlavaForConditionalGeneration(nn.Module, SupportsMultiModal, SupportsPP):
 
-    def __init__(self, vllm_config: VllmConfig, prefix: str = "") -> None:
+    def __init__(self, *, vllm_config: VllmConfig, prefix: str = "") -> None:
         super().__init__()
 
         config = vllm_config.model_config.hf_config