Small bug, typo

app.py

@@ -41,11 +41,12 @@ class Harold:
         return system_prompt
 
     def chat(self, message, history):
-        messages = [{"role:": "system", "content": self.system_prompt()}] + history + [{"role:": "user", "content": message}]
+        messages = [{"role": "system", "content": self.system_prompt()}] + history + [{"role": "user", "content": message}]
 
         response = self.openai_client.chat.completions.create(
             model="gpt-4o-mini",
             messages=messages,
+            stream=True,
         )
         return response.choices[0].message.content