Remove unused dependency

modeling_nova.py

@@ -5,7 +5,7 @@ import torch.nn as nn
 import torch.nn.functional as F
 from typing import Tuple, List, Optional
 from transformers import LlamaModel, LlamaConfig, LlamaForCausalLM
-from transformers.models.llama.modeling_llama import LlamaDecoderLayer, LLAMA_ATTENTION_CLASSES, LlamaMLP, LlamaRMSNorm
+from transformers.models.llama.modeling_llama import LlamaDecoderLayer, LlamaMLP, LlamaRMSNorm
 from transformers.models.llama.modeling_llama import LlamaSdpaAttention, apply_rotary_pos_emb, repeat_kv
 from transformers import logging, Cache, DynamicCache, StaticCache
 from transformers.modeling_outputs import BaseModelOutputWithPast, CausalLMOutputWithPast