Update yarn version in dev installation documentation

[trungleduc]

No description provided.

[github-actions]

👈 Launch a binder notebook on branch trungleduc/ipywidgets/update-dev-doc

[maartenbreddels]

I thought we needed <2 everywhere, and this is also what is in https://github.com/jupyter-widgets/ipywidgets/blob/main/docs/source/dev_release.md and what I used for releasing.

[trungleduc]

I saw It is bumped to version 3 in the readme in the last PR. The yarn 1 config file is also replaced with the yarn 3 one.

[ferdnyc]

I saw It is bumped to version 3 in the readme in the last PR. The yarn 1 config file is also replaced with the yarn 3 one.

Yeah, actually the bump to requiring Yarn 3 was done in 8c08faf — I just updated the README and the Binder scripting to match, plus shook out some of the consequences of the change (like dropping a yarn plugin that's only compatible with version 1).

Looks like https://github.com/jupyter-widgets/ipywidgets/blob/main/docs/source/dev_release.md should be updated as well. Running yarn set version stable from the ipywidgets repo root directory will switch to using Yarn 3 locally, even on systems where the yarn command is otherwise version 1.