message: fix: remove unnecessary arg value existence check
diff: @@ -15,7 +15,7 @@ pub fn cli() -> App {
  pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
  let ws = args.workspace(config)?;
  - if !args.is_present("spec") && args.is_present_with_zero_values("package") {
  + if args.is_present_with_zero_values("package") {
  print_available_packages(&ws)?
  }
  let spec = args.value_of("spec").or_else(|| args.value_of("package"));
  