fix: don't error when crate is missing description

Author: Pacman99

crate2nix/templates/nix/crate2nix/default.nix

@@ -455,7 +455,7 @@ rec {
                     assert (lib.assertMsg (crateConfig ? sha256) "Missing sha256 for ${name}");
                     crateConfig.sha256;
                 });
-              meta = {
+              meta = lib.optionalAttrs (crateConfig ? description) {
                 inherit (crateConfig) description;
               };
               inherit