setuptools missing in setup.py/install_requires

[ZdenekM]

pkg_resources (part of setuptools) is imported, but the dependency is missing. Would it be possible to add it?

[lafrech]

Or define the version in the init file, and in setup.py either duplicate it or parse it like is done in marshmallow.

https://github.com/marshmallow-code/marshmallow/blob/7510fac06ac476db8b666ef94d4764ad1c208640/setup.py#L23-L37