setup.py: Add a python_requires field

This field instructs tools like pip and setup tools about which versions
of python you support. In alot's case that is currently 2.7.x

Fixes #1118

1 files changed, 1 insertions, 0 deletions

diff --git a/setup.py b/setup.py
index fc99e46c..262b0bf0 100755
--- a/setup.py
+++ b/setup.py
@@ -53,4 +53,5 @@ setup(
     ],
     provides=['alot'],
     test_suite="tests",
+    python_requires=">=2.7,<3.0",
 )