Remove `punycode` polyfill

[tre2man]

The funycode seems to be deprecated.

(node:43949) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.

[Richienb]

This is a problem with your code: your code is importing the punycode module, which is deprecated.

Instead, install the similarly named punycode userland module from npm and import it like require('punycode/'), noting the forward slash (/).

[Richienb]

I think it is worth stopping polyfilling punycode since there is no longer any practical use now. (maybe time to separate out into compat- and recommended- configs)?