update model to 4o-mini

app.py

@@ -74,8 +74,8 @@ retriever = vectorstore.as_retriever(
 )
 
 llm = ChatOpenAI(
-    model="gpt-4",
-    temperature=0.1,
+    model="gpt-4o-mini",
+    temperature=0,
     streaming=True,
 )