[Cython] Ready for Cython 3.1 ?

[Stefan Behnel]

Stefan Behnel schrieb am 05.11.23 um 23:06:
> I'd like to ease our feature development by using more modern Python 
> features in our code base and by targeting less Python versions in Cython 
> 3.1 compared to the "all things supported" Cython 3.0.

I created a 3.0.x maintenance branch and removed the Py<3.7 test jobs from 
the master branch. That should make the CI response visibly faster.

Happy code cleaning :)

Stefan