fix: `escapeArg` was not escaping multiple quotes

[Ryooooooga]

import $ from "https://deno.land/x/dax/mod.ts";
import $2 from "./mod.ts"; // this branch

await $2`echo ${`'abc'`}`; // 'abc'
await $`echo ${`'abc'`}`; // error: Uncaught "Expected closing single quote.\n  '\n  ~"