Pass python_requires argument to setuptools (#636)

Helps pip decide what version of the library to install.

https://packaging.python.org/guides/distributing-packages-using-setuptools/#python-requires

> If your project only runs on certain Python versions, setting the
> python_requires argument to the appropriate PEP 440 version specifier
> string will prevent pip from installing the project on other Python
> versions.

https://setuptools.readthedocs.io/en/latest/setuptools.html#new-and-changed-setup-keywords

> python_requires
>
> A string corresponding to a version specifier (as defined in PEP 440)
> for the Python version, used to specify the Requires-Python defined in
> PEP 345.

1 files changed, 1 insertions, 0 deletions

diff --git a/setup.py b/setup.py
index c0bdf38..3f822e0 100755
--- a/setup.py
+++ b/setup.py
@@ -36,6 +36,7 @@ setup(
     platforms='any',
     license='BSD',
     packages=find_packages(exclude=('docs', 'tests', 'tests.*')),
+    python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
     extras_require={
         'rsa': rsa_require,
         'signedtoken': signedtoken_require,