[data] fix: update parquet_files type check to support multi-file input (volcengine#3211)

Author: looput

verl/utils/dataset/multiturn_sft_dataset.py

@@ -22,6 +22,7 @@
 import numpy as np
 import pandas as pd
 import torch
+from omegaconf import ListConfig
 from torch.utils.data import Dataset
 from transformers import PreTrainedTokenizer
 
@@ -60,7 +61,7 @@ def __init__(self, parquet_files: str | list[str], tokenizer, config=None):
         self.apply_chat_template_kwargs = config.get("apply_chat_template_kwargs", {})
         assert self.truncation in ["error", "left", "right"]
 
-        if not isinstance(parquet_files, list):
+        if not isinstance(parquet_files, list | ListConfig):
             parquet_files = [parquet_files]
 
         self.parquet_files = parquet_files