Remove non-existant pypy3 version from travis build.
Remove non-existant pypy3 version from travis build.

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