Replace PY_NEW and PY_NEW_SAME_TYPE by __new__() method #17668
Description
Change this everywhere except for Integer and RealDoubleElement classes, which use a custom hooked tp_new that Cython isn't aware of.
Component: cython
Author: Jeroen Demeyer
Branch/Commit: 47217bc
Reviewer: Marc Mezzarobba
Issue created by migration from https://trac.sagemath.org/ticket/17668