Test application automatically

Testing a streamlit application is not straightforward. A few hints:

• https://blog.streamlit.io/testing-streamlit-apps-using-seleniumbase/
• https://blog.devgenius.io/testing-streamlit-a1f1fd48ce8f
• https://discuss.streamlit.io/t/check-if-running-in-a-streamlit-session/842/6