Add CI

[jtpio]

Problem

CI does not run on the repo at the moment.

Proposed Solution

It would be great to add the workflows that should be generated automatically when bootstraping the kernel with the cookiecutter: https://github.com/jupyterlite/serverlite-cookiecutter-ts

So folks making releases with the Jupyter Releaser are confident the release will work.

Additional context

Looks like a manual release has already been pushed to PyPI: https://pypi.org/project/jupyterlite-xeus-nelson

[martinRenou]

This is now fixed