py-cython: updated to 0.29.28

0.29.28 (2022-02-17)
====================

Bugs fixed
----------

* Due to backwards incompatible changes in CPython 3.11a4, the feature flags
  ``CYTHON_FAST_THREAD_STATE`` and ``CYTHON_USE_EXC_INFO_STACK`` are now disabled
  in Python 3.11 and later.  They are enabled again in Cython 3.0.
  Patch by David Woods.

* A C compiler warning in older PyPy versions was resolved.
  Patch by Matti Picus.

(adam)