use latest versions of python and jupyter-book

[PhiSpel]

Description

closes #460
like #458 but with cards instead of grid-item-card

Checklist

• This pull request is associated to an issue
• Add someone else as reviewer and wait for approval before merging.

[PhiSpel]

Now, it looks better, see here.

Only remaining issue is that the CSS variable --sd-color-card-header needs to be changed to #00000008 instead of transparent, see here. I just need to find the right file to put this information...

...I may be able to set class-header

[PhiSpel]

running the "live code" function does not work, as the kernel seems to run on python instead of octave (it does work correctly in mybinder). This is different, for example, in #438

[PhiSpel]

@Florian314 what do you think about the layout, for example here?

[PhiSpel]

Usually, one should be able to define custom styles in a _static/custom.css file within the project directory. I am afraid this is not accessed by jupyter book, see e9abf86

These colors are accessible by the :header-style: keyword, of which bg-light seems to be the most sensible.

So, @Florian314, please look at the layout of the cards in "Das Stauproblem - Motivation zur Benutzung dieses Buches" and "Verwendung dieses Buches". What's your opinion on them?

When I have the feedback, I can adapt the 40-some other files.

[Florian314]

The box in a box looks strange to me

[Florian314]

This looks the best if you can delet the line below "Voraussetzungen"

[PhiSpel]

Actually, I just realized, that the boxes are now the same as the old ones:

@Florian314 Isn't this just fine / even better?

[Florian314]

yeah, i personely like the old ones the most