Update to ipywidgets 8 / Notebook 7 / JupyterLab 4

[martinRenou]

Builds against twosigma/beakerx_base#10 and twosigma/beakerx_kernel_groovy#17

[martinRenou]

This does not work yet. There is some CodeMirror tweaking logic that does not work with JupyterLab 4 (CodeMirror 6).

This will require some days of work to get it right. Also we might want to consider dropping JupyterLab <=3 support, because supporting multiple CodeMirror versions may be tricky.

[martinRenou]

This is now working nicely.

We need to update the beakerx_test repository in order for the e2e tests to pass.

[achhina]

@martinRenou would this warrant a bump in version number?

[martinRenou]

Compatibility should be kept for JupyterLab 3.

As long as you built the wheel in an environment where JupyterLab 4 lives, the resulting wheel can be installed in an environment where JupyterLab 3 is installed.

So I guess a 2.4.0 bump is enough.

[martinRenou]

@achhina I think this is ready for merging. We can bump the version number separately.