Set up and publish next major release

[RRosio]

This issue will outline the steps we need to take to configure Gator for automated releases, including publishing to PyPI and GitHub

• Request maintainers be added to the PyPI project
• Prepare to use jupyter_releaser
  • Setup trusted publishers in PyPI and the Github app secret with repo and workflow scope
• Create release workflows .github/workflows/*

[danyeaw]

We discussed this today, and we'll do a manual release this time and then we can try to make use of jupyter_releaser and automation for the following release.

[RRosio]

v6.0.0 has now been released on both GitHub and PyPI