Bump cython from 0.29.7 to 0.29.9 (#99)

Bumps [cython](https://github.com/cython/cython) from 0.29.7 to 0.29.9.
- [Release notes](https://github.com/cython/cython/releases)
- [Changelog](https://github.com/cython/cython/blob/master/CHANGES.rst)
- [Commits](https://github.com/cython/cython/compare/0.29.7...0.29.9)

requirements.dev.txt

 flake8==3.7.7
-Cython==0.29.7
+Cython==0.29.9
 nose==1.3.7
 pylint==1.9.4
 pytest==4.4.1