Fix psutils licence.

pkgs/tools/typesetting/psutils/default.nix

···
   meta = with stdenv.lib; {
     description = "Collection of useful utilities for manipulating PS documents";
     homepage = http://knackered.knackered.org/angus/psutils/;
-    license = licenses.bsd;
+    license = licenses.bsd3;
   };
 }