Treewide: update some problematic homepages

These URLs are reported as problematic by Repology.
It could be a permanent redirection
or the page does not exist anymore

pkgs/development/python-modules/mox/default.nix

@@ -16,7 +16,7 @@ buildPythonPackage rec {
   doCheck = false;
 
   meta = with stdenv.lib; {
-    homepage = http://code.google.com/p/pymox/;
+    homepage = "https://pymox.readthedocs.io/";
     description = "A mock object framework for Python";
     license = licenses.asl20;
   };