Changed python version control.

Author: MaxBlesch

ruspy/ruspy_config.py

@@ -6,7 +6,7 @@
 
 # We only support modern Python.
 np.testing.assert_equal(sys.version_info[0], 3)
-np.testing.assert_equal(sys.version_info[1] >= 5, True)
+np.testing.assert_equal(sys.version_info[:2] >= (3, 6), True)
 
 # We rely on relative paths throughout the package.
 PACKAGE_DIR = os.path.dirname(os.path.realpath(__file__))