Module `punycode` is deprecated since Node.js 21

This library depends on the [`punycode` builtin module](https://nodejs.org/docs/latest/api/punycode.html)... but since Node.js 21, this module is deprecated:

```
(node:4284) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.
```