Fix syntax error

app.py

@@ -43,7 +43,7 @@ st.markdown(
 )
 
 # Define the placeholder globally (outside columns)
-if('conversation' not in st.session_state)
+if('conversation' not in st.session_state):
     placeholder = st.empty()
     placeholder.markdown(f'<div class="scrollable-div"><p>Welcome! I am your Adrega AI assistant</p></div>', unsafe_allow_html=True)