Streamline the release process

[jaraco]

Just have a look at the docs for releasing. 21 steps with timing constraints. Yikes.

Let's see if we can't pare this down and automate most of the process.

[sigmavirus24]

I believe that was when we had a top-notch consultant assisting with the release process. They wanted to be extraordinarily clear about the steps so anyone could do it. Could we have written the steps more succinctly? Maybe.

I think the steps about uploading to Test PyPI first are good and help with validation.

I suspect we could do downstream test integrations in CI for each PR to skip some of those steps but at a skim now, I don't see how we could automate very much without sacrificing quality.

[jaraco]

That's good feedback. I've started on some in feature/test-devpi to automate the tests with devpi. I'd like to do something similar for Test PyPI. In some ways this is a meta ticket and will be addressed by a number of pull requests.