[Qwen3.5] Fix missing quant_config in Qwen3VL (#19291)

Author: mmangkad

python/sglang/srt/models/qwen3_vl.py

@@ -1025,6 +1025,7 @@ def __init__(
     ) -> None:
         super().__init__()
         self.pp_group = get_pp_group()
+        self.quant_config = quant_config
 
         self.use_data_parallel = get_global_server_args().mm_enable_dp_encoder