from setuptools import setup, find_packages

setup(
    name = "greengraph",
    version = "0.1",
    install_requires = ['geopy','numpy','matplotlib','requests','StringIO']
)

from setuptools import setup, find_packages

setup(
    name = "greengraph",
    version = "0.1",
    install_requires = ['geopy','numpy','matplotlib','requests']
)

Remove StringIO from required packages in setup.py.