Update "Release process" docs

[tpvasconcelos]

Update the "Release process" docs to reflect the current status.

Potentially relevant references:

• https://github.com/pypa/gh-action-pypi-publish
• https://packaging.python.org/en/latest/guides/publishing-package-distribution-releases-using-github-actions-ci-cd-workflows/
• https://github.com/python-pillow/Pillow/blob/109c6bf6c0abc00c37b0819ebd573390647692e4/pyproject.toml#L89C7-L94
• https://github.com/pypa/cibuildwheel/blob/main/examples/github-deploy.yml
• https://cibuildwheel.readthedocs.io/en/stable/

[fkiraly]

here's sktime's, in case it would be helpful:

https://www.sktime.net/en/stable/developer_guide/release.html

[tpvasconcelos]

Great reference! Thanks @fkiraly