[SIGMON-549] migrate to matplotlib widgets

Context

• Our Jupyter notebook from the 'legacy' backend_nbagg backend provided by Matplotlib (invoked with the magic command %matplotlib notebook)
• No support for interactive plots in VS Code (see https://github.com/microsoft/vscode-jupyter/wiki/Using-%25matplotlib-widget-instead-of-%25matplotlib-notebook,tk,etc)
• Issue causing the Matplotlib version to be frozen (see https://swan-community.web.cern.ch/t/bug-in-interactive-matplotlib-plots-in-swan-notebooks/419)

What was done

• Replace % matplotlib notebook by % matplotlib widget
• Test in SWAN that the new backend works
• Check with Zinur that the functionality offered was the same
• Remove the fixed version for Matplotlib
• Change the CI test to match the new SWAN package versions

TODO

• ?

QA

• code was not unit tested, because...
• acceptance tests were written

Review objectives

• assessment of code functionality
• assessment of code quality