Update app.py

app.py

@@ -1,6 +1,6 @@
 from datasets import load_dataset, Dataset
 from huggingface_hub import HfApi, Repository
-
+import os
 # Configurations
 source_dataset_name = "nvidia/Nemotron-Personas"   # example dataset
 columns_to_keep = ["persona", "sex", "age"]  # example columns to extract