Expose package itself from the flake

[paluh]

Hello,

thanks a lot for putting this useful tool together. One blocker which I found is that flake.nix does not expose the package itself (I'm not able to use your shell I want to include the tool inside my shell where I provide cardano-node myself). Should I open a PR with something like:

packages.cardonnay = pkgs.python313.pkgs.buildPythonApplication {
  pname = "cardonnay";
  version = "0.3.4";
  src = self;
  pyproject = true;

  build-system = with pkgs.python313.pkgs; [ setuptools setuptools-scm ];

  SETUPTOOLS_SCM_PRETEND_VERSION = "0.3.4";

  nativeBuildInputs = with pkgs.python313.pkgs; [ pythonRelaxDepsHook ];

  pythonRelaxDeps = [ "setuptools" ];

  dependencies = with pkgs.python313.pkgs; [
    supervisor click pygments pydantic filelock
  ];
};

[mkoura]

Thanks for your feedback. Please open the PR.