Update app.py

gpt4 test for retreival

app.py

@@ -32,7 +32,7 @@ def pdf_changes(pdf_doc):
         retriever = db.as_retriever()
         global qa
         qa = ConversationalRetrievalChain.from_llm(
-            llm=OpenAI(temperature=0.2, model_name="gpt-4-1106-preview", max_tokens=-1, n=2),
+            llm=OpenAI(temperature=0.2, model_name="gpt-4", max_tokens=-1, n=2),
             retriever=retriever,
             return_source_documents=False
         )