pythonPackages.django_raster: Use mirror in URL

pkgs/top-level/python-packages.nix

···
   };
 
   django_raster = buildPythonPackage rec {
-    name = "djongoraster-${version}";
+    name = "django-raster-${version}";
     version = "0.2";
 
     src = pkgs.fetchurl {
-      url = "https://pypi.python.org/packages/09/3d/5b9b491186579825ef6e81d60c8ddaf86d8c98d928753a329980bf48b050/django-raster-0.2.tar.gz";
+      url = "mirror://pypi/d/django-raster/${name}.tar.gz";
       sha256 = "1zdcxzj43qrv7cl6q9nb2dkfnsyn74dzf2igpnd6nbbfdnkif9bm";
     };