Update app.py to solve the rerun error

app.py

@@ -100,7 +100,7 @@ if st.button("✅ Submit Answers"):
         st.session_state.level += 1
         st.session_state.questions = generate_questions(st.session_state.level)
         st.session_state.start_time = time.time()  # Reset timer
-        st.experimental_rerun()
+        st.rerun()
 
 # Show total score
 st.sidebar.markdown(f"## Total Score: {st.session_state.score}")