Fetch the ATeL text if not given

I introduced a function to fetch the ATeL text and modified the notebook so that by default, no text is given. If the text is not given, it fetches the ATeL number from the website, otherwise it uses the text.

My changes refer just to the two commits that I made (I had to add beatifulsoup4 in the environment.yml), but I see many auxiliary files changed in this merge request. I do not know what I should do with them.