[7.x] Pin to jupyterlab_widgets>=1.0.0,<3

[jtpio]

As noticed in jupyterlab/jupyterlab#12962 and jupyterlab/jupyterlab#12967, the JupyterLab UI tests were affected by the ipywidgets 8 release even though they pin on ipywidgets==7.6.5.

This had to do with jupyterlab_widgets==3 being pulled when installing ipywidgets==7.6.5.

This PR proposes pinning the version of jupyterlab_widgets for the 7.x release series to avoid mismatches.

[jtpio]

For reference the current master branch (8.x) pins on ~=3.0:

ipywidgets/python/ipywidgets/setup.cfg

Line 41 in 89026e1

jupyterlab_widgets~=3.0

[vidartf]

Actually, the 2.x version was reserved for 7.x support for lab 4. This might not be released if the lumino 2 upgrade precludes this, but it should still be safe to use <3 in the pin/

[jtpio]

Good point, I updated the pin to jupyterlab_widgets>=1.0.0,<3 in 46b9d8d

[jasongrout]

How far back should we backport this? Perhaps to 7.7 and 7.6?

[jasongrout]

7.6.0 was released 24 Dec 2020, so porting back to 7.6.x gives us almost about 1.5 years of support for the old 7.x releases, and corresponds to the jlab 3.0 release the day before. I think that's probably good enough. If people need to pin farther back than that, they'd have to do it anyway based on their jlab version.

tldr; I think we should backport this to 7.6.x as well.

[jtpio]

Perhaps to 7.7 and 7.6?

Sounds good 👍

[jasongrout]

I spent some time investigating the test failure, but I'm not seeing the root cause. I believe it is just in the development install, though, so given the severity of this issue, I'll go ahead and merge and release, and we can follow up about the development install.