Update modeling_custom_seq2seq_llm.py

modeling_custom_seq2seq_llm.py

@@ -7,6 +7,7 @@ from flash_atten import MHA  # Import the MHA class from the provided implementa
 from liger_kernel.transformers.cross_entropy import LigerCrossEntropyLoss
 from liger_kernel.transformers.rms_norm import LigerRMSNorm
 from liger_kernel.transformers.swiglu import LigerSwiGLUMLP
+from transformers import PreTrainedModel
 
 from configuration_custom_seq2seq_llm import Seq2SeqConfig