Pin min notebook version

[mathbunnyru]

Describe your changes

Issue ticket if applicable

Checklist (especially for first-time contributors)

• I have performed a self-review of my code
• If it is a core feature, I have added thorough tests
• I will try not to use force-push to make the review process easier for reviewers
• I have updated the documentation for significant changes

[mathbunnyru]

jupyterlab 4.3.0 has been released, but the new notebook which supports this version hasn't yet.

Unfortunately, previous versions of notebook (<v7) didn't have a version restriction on jupyterlab, so the solver installs jupyterlab 4.3.0 and notebook 6.5.7 (and obviously it doesn't work)

To fix this problem, I decided to pin the minimum notebook version.
We might need to keep this pin forever so we don't have the same problem with new releases of jupyterlab.

@krassowski @minrk @bollwyvl do you maybe know a better solution?

[mathbunnyru]

Merging this, because currently, our builds are failing.
Please let me know, if there is a better solution.