[Cython] Preparing the first alpha release of Cython 3.0

[Stefan Behnel]

Hi all,

I'm curently preparing a first alpha release for Cython 3.0 (alpha 1).

Please ping me on any open pull requests that you think are ready and
should be included.

Note that this is not the end of the journey – anything that's not included
right now can still come in later, before the first beta. (That's later
this year, before you ask.) There will definitely be at least one more
alpha release before we get even there.

So, please concentrate on changes for this release that have a potentially
disruptive user impact, so that our users can start preparing their code
and/or complain early in order to keep us from making The One Big Mistake
of breaking their code.

Thanks,
Stefan