Fix typo

app.py

@@ -127,7 +127,7 @@ if "openai_model" not in st.session_state:
 if "messages" not in st.session_state:
     current_date = datetime.now().strftime("%Y-%m-%d")
     # st.session_state.messages = [{"role": "system", "content": f"現在的日期: {current_date}"}]
-    st.session_state.messages = [{"role": "system", "content": SYSTEM_PROMPT]
+    st.session_state.messages = [{"role": "system", "content": SYSTEM_PROMPT}]
 
 for message in st.session_state.messages:
     if message['role'] == "system": continue