pythonPackages.cgroup-utils: Linux only

https://hydra.nixos.org/build/61731047

pkgs/development/python-modules/cgroup-utils/default.nix

···
   meta = with stdenv.lib; {
     description = "Utility tools for control groups of Linux";
     maintainers = with maintainers; [ layus ];
+    platforms = platforms.linux;
     license = licenses.gpl2;
   };
 }