Relax requirement for defusedxml

It allows to install newer version of defusedxml library from EPEL repository: python2-defusedxml-0.5.0

Author: AmbientLighter

setup.py

@@ -59,6 +59,6 @@ def read(*rnames):
     zip_safe=False,
     install_requires=[
         'pysaml2==4.4.0',
-        'defusedxml==0.4.1'
+        'defusedxml>=0.4.1'
         ],
     )