bug#58490: Add python-jupytext.

[Ricardo Wurmus]

Hi,

I applied these patches with a number of changes.

- removed @code{} syntax around proper names
- removed unnecessary build phase
- fixed indentation
- used single semicolon for line comments
- did not apply patch for python-sphinx-gallery-0.7.0 because it’s not
  needed
- use git-minimal

Thanks for the patches!

-- 
Ricardo