python312Packages.pegen: refactor

buildPythonPackage rec {

  pname = "pegen";

  version = "0.3.0";

  format = "pyproject";

  pyproject = true;

  disabled = pythonOlder "3.8";

  src = fetchFromGitHub {

    owner = "we-like-parsers";

    repo = pname;

    repo = "pegen";

    tag = "v${version}";

    hash = "sha256-P4zX8za9lBlXhNPkQe9p136ggZEJh6fHfBr+DQKvtTg=";

  };

  nativeBuildInputs = [

  build-system = [

    setuptools

    setuptools-scm

  ];