python3Packages.rich-rst: add setuptools to nativeBuildInputs

pkgs/development/python-modules/rich-rst/default.nix

···
 { lib
 , buildPythonPackage
 , fetchFromGitHub
+, setuptools
 , docutils
 , rich
 }:
···
     rev = "v${version}";
     sha256 = "sha256-s48hdJo1LIRXTf+PeSBa6y/AH1NLmnyAafFydJ+exDk=";
   };
+
+  nativeBuildInputs = [
+    setuptools
+  ];
 
   propagatedBuildInputs = [ docutils rich ];