Recompile with new Cython

[StrikerRUS]

Fixed #153.

Linking previous recompilation: #134.

Root cause:

The tp_print slot of PyTypeObject has been removed. It was used for printing objects to files in Python 2.7 and before. Since Python 3.0, it has been ignored and unused. (Contributed by Jeroen Demeyer in bpo-36974.)
https://docs.python.org/dev/whatsnew/3.9.html#id3

https://docs.python.org/3/c-api/typeobj.html#c.PyTypeObject.tp_vectorcall_offset

Proof that it works:
https://github.com/BayesWitnesses/m2cgen/blob/979fbd8b1ae048f2a843f59e2c2755c75dd816ac/requirements-test.txt#L6
https://github.com/BayesWitnesses/m2cgen/pull/371/checks?check_run_id=2428248886

Gently ping @mblondel @MechCoder @zermelozf @fabianp @vene according to

The project is indeed no longer actively maintained but hot fixes like this to follow the latest scikit-learn are very welcome.
#142 (comment)

Also, I believe this hotfix deserves a new PyPI release to make this package compatible with Python 3.9.

Thanks for your time.

[mblondel]

Thanks @StrikerRUS! Is random_fast.cpp the only file that needed to be recompiled?

[StrikerRUS]

@mblondel Thanks for your response!

Yes. randomkit.h and randomkit.c are not produced via Cython but they are ordinary manually written files. And there are no any other C or CPP files in the repo.

[StrikerRUS]

TBH, I'm very familiar with Cython, but why random_fast.cpp is not produced on the fly like all other CPP files in impl folder from corresponding *_fast.pyx files?

[mblondel]

Good point. The cpp files used to be included and they got removed in f54f041 by @lesteve. I think random_fast.cpp should be removed too, it's probably an omission.