[Cython] Cython 3.0 final released

[Stefan Behnel]

Hi all,

after close to five long years, I'm proud to announce the release of
Cython 3.0. It's done. It's out. Finally!

The full list of improvements compared to the 0.29.x release series is 
entirely incredible.

https://cython.readthedocs.io/en/latest/src/changes.html

Cython 3.0 is better than any other Cython release before, in all aspects. 
It's much more Python, integrates better with C and C++, supports more 
Python implementations and configurations, provides many great new language 
features
	– it's faster, safer and easier to use. It's simply better.

New language features include:

- Python 3 syntax and semantics by default
- Cython type annotations in plain Python code
- automatic NumPy ufunc generation
- fast @dataclass and @total_ordering extension types
- safe exception propagation in C functions by default
- Unicode identifiers in Cython code

All of this wouldn't have been possible without the help of the many, many 
people who contributed code and documentation, tested features, found and 
described bugs, helped debugging problems. Those who started using Cython 
in new environments, new build systems, new use cases, and helped to get it 
working there. Who proposed new features or found mismatches and gaps in 
the existing set of features.

Thank you all, you helped making Cython 3.0 an awesome language!

Along the way, we added two people to the list of Cython developers.

* David Woods has contributed a tremendous list of features and fixes to 
this release. It would honestly not have been possible without his efforts.

* Matúš Valo has put a lot of work into the documentation and the pure 
Python mode. He found many issues that make Cython now easier and more 
consistent to use from Python code.

Thank you both for your contributions. I'm happy to work together with you.

Everyone, have fun using Cython 3.0, and whatever good comes after it.

Best,
Stefan