Add ESM exports

[Gobd]

Here's an issue from jsonwebtoken for the same auth0/node-jsonwebtoken#655 I think it would be nice to do this here and maybe encourage people to switch to this library.

[andolivieri-nf]

hello @Gobd, is there any specific reason/issue to do so? Library should already work fine with ESM

[Gobd]

I guess just supporting the latest standards. As time goes on more and more people will want everything to be ESM so might as well get going now.

[simoneb]

@Gobd I get your point but CJS modules are entirely usable from ESM, so I'm wondering if there any specific scenario that you have in mind.

[Gobd]

Closing, congrats on defending against the future standards.