Widgets don't show up in notebook

[l0b0]

While working on #74 I noticed that widgets don't seem to show when run. Take for example this snippet:

import ipywidgets
ipywidgets.IntProgress(value=0, min=0, max=1)

If I run this in flooding/sentinel2_water_extraction/sentinel2_water_extraction.ipynb I would expect a widget to show up, but instead I see nothing. Based on similar issues elsewhere it seems like I need to move from the "plain" jupyter package to jupyterlab.