fix sglang backend

Author: shell-nlp

gpt_server/model_backend/sglang_backend.py

@@ -10,7 +10,6 @@
 import sglang as sgl
 from transformers import PreTrainedTokenizer
 from sglang.utils import convert_json_schema_to_str
-from sglang.srt.conversation import generate_chat_conv
 
 from qwen_vl_utils import process_vision_info
 from sglang.srt.managers.io_struct import GenerateReqInput