Remove unused code for the with-dependencies flag

The flag was not implemented and the getter method now panics for
unknown argument or group ids.

src/bin/modiom/commands/download.rs

@@ -39,7 +39,6 @@ pub fn cli() -> Command {
 pub fn exec(config: &Config, args: &ArgMatches) -> CliResult {
  let game_id = *args.get_one("game-id").expect("required arg");
  let mod_ids = args.get_many("mod-id").expect("required arg");
- let _with_deps = args.get_flag("with-dependencies");
  let dest = args.get_path("dest").map(Cow::from).unwrap_or_default();
 
  let rt = Runtime::new()?;