Update to jupyterlite==0.1.0b17

[jtpio]

Update to the latest jupyterlite release: https://github.com/jupyterlite/jupyterlite/releases/tag/v0.1.0b17

In this release the piplite_urls configuration has changed and should be provided under PipliteAddon: https://jupyterlite.readthedocs.io/en/latest/howto/python/wheels.html

[github-actions]

👈 Launch a binder notebook on branch jtpio/ipywidgets/update-jupyterlite-b17

[jtpio]

The docs build still seems to be failing: https://readthedocs.org/projects/ipywidgets/builds/19070899/

Command killed due to timeout or excessive memory consumption

Which also seems to be the case on other PRs.

[bollwyvl]

#3673 updated to b18, and #3674 fixes the PipliteAddon API change, so this can likely be closed.

[jasongrout]

Thanks! Closing since it is superseded by Nick's PR.