remove unused import

llama_finetuning.py

@@ -66,7 +66,6 @@ import torch
 import torch.nn as nn
 import torch.cuda.nccl as nccl
 import torch.distributed as dist
-from torch.distributed.fsdp._common_utils import _is_fsdp_flattened
 from transformers.models.llama.modeling_llama import LlamaDecoderLayer