[Fix] Type annotation correction for UpdateWeightsFromTensorReqInput (#4532)

Co-authored-by: Zhiqiang Xie <xiezhq@stanford.edu>

python/sglang/srt/managers/io_struct.py

@@ -540,7 +540,8 @@ class UpdateWeightsFromDistributedReqOutput:
 
 @dataclass
 class UpdateWeightsFromTensorReqInput:
-    serialized_named_tensors: bytes  # indeed Dict[str, torch.Tensor]
+    # List containing one serialized Dict[str, torch.Tensor] per TP worker
+    serialized_named_tensors: List[bytes]
     load_format: Optional[str]
     flush_cache: bool