Update app.py

app.py

@@ -84,6 +84,9 @@ qa_embeddings = semantic_model.encode(qa_questions, convert_to_tensor=True)
 #-------------------------bm25---------------------------------
 from rank_bm25 import BM25Okapi
 from nltk.tokenize import word_tokenize
+import nltk
+nltk.download('punkt')
+
 
 def rerank_with_bm25(docs, query):
     tokenized_docs = [word_tokenize(doc['content'].lower()) for doc in docs]