- Version update to 0.28.1:
* PyFrozenSet_New() was accidentally used in PyPy where it is lacking
from the C-API.
* Assignment between some C++ templated types were incorrectly rejected
when the templates mix const with ctypedef. (Github issue #2148)
* Undeclared C++ no-args constructors in subclasses could make the
compilation fail if the base class constructor was declared without
nogil. (Github issue #2157)
* Bytes %-formatting inferred basestring (bytes or unicode) as result type
in some cases where bytes would have been safe to infer. (Github issue #2153)
* None was accidentally disallowed as typed return value of dict.pop().

- update to version 0.28:
* Features added
+ Cdef classes can now multiply inherit from ordinary Python
classes. (The primary base must still be a c class, possibly
object, and the other bases must not be cdef classes.)
+ Type inference is now supported for Pythran compiled NumPy
expressions. Patch by Nils Braun. (Github issue #1954)
+ The const modifier can be applied to memoryview declarations to
allow read-only buffers as input. (Github issues #1605, #1869)
+ C code in the docstring of a cdef extern block is copied
verbatimly into the generated file. Patch by Jeroen
Demeyer. (Github issue #1915)
+ When compiling with gcc, the module init function is now tuned
for small code size instead of whatever compile flags were
provided externally. Cython now also disables some code
intensive optimisations in that function to further reduce the
code size. (Github issue #2102)
+ Decorating an async coroutine with @cython.iterable_coroutine