update version

setup.py

@@ -8,7 +8,7 @@
 # Always prefer setuptools over distutils
 from setuptools import setup, find_packages
 # Get the long description from the README file
-version = 2.6.0
+version = "2.6.0"
 # Taken from https://stackoverflow.com/questions/14399534/reference-requirements-txt-for-the-install-requires-kwarg-in-setuptools-setup-py/14399775#14399775
 with open('requirements.txt') as fp:
     required = fp.read().splitlines()