ci/test: use bare ipython instead of nbval

[Borda]

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you make sure to update the docs?
• Did you write any new necessary tests?

What does this PR do?

We do not use any real test in the notebooks as added notebooks are without any output so there is nothing to match except just all cells are passing, but there is some issue with cell's timeout

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[codecov]

Codecov Report

Attention: Patch coverage is 70.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 71%. Comparing base (d047ff8) to head (54196f3).

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #324   +/-   ##
===================================
- Coverage    71%    71%   -0%     
===================================
  Files         2      2           
  Lines       399    401    +2     
===================================
  Hits        285    285           
- Misses      114    116    +2