Add appveyor build for Py3.8 (will probably fail tests, but it should at least build).
Add appveyor build for Py3.8 (will probably fail tests, but it should at least build).

scoder/cython,cython/cython,da-woods/cython,da-woods/cython,scoder/cython,cython/cython,da-woods/cython,scoder/cython,cython/cython,scoder/cython,da-woods/cython,cython/cython