sage: python-openid: move django and twill to checkInputs (#54949)

A search through the source code
(https://github.com/openid/python-openid/search?q=django and
https://github.com/openid/python-openid/search?q=twill) reveals
that they are only used in examples and tests.

pkgs/applications/science/math/sage/python-openid.nix

@@ -20,15 +20,13 @@ buildPythonPackage rec {
   };
 
   propagatedBuildInputs = [
-    django
-    twill
     pycrypto
   ];
 
   # Cannot access the djopenid example module.
   # I don't know how to fix that (adding the examples dir to PYTHONPATH doesn't work)
   doCheck = false;
-  checkInputs = [ nose ];
+  checkInputs = [ nose django twill ];
   checkPhase = ''
     nosetests
   '';