Replace axios with native fetch

[mattt]

Related to #29 (comment)

The decision to use axios was entirely pragmatic — it was the first thing I got working, so I went with that. I'd be very open to dropping it entirely for fetch if that works cross-platform reasonably well.

This PR should do exactly that. I'm out of the loop about preferred fetch polyfill libraries and other packaging concerns, so if you have any strong opinions, please let me know!

[mattt]

All of our tests currently stub out request, so there's currently no way to tell if this actually works. We should update our test suite to stub or mock fetch responses or support smoke testing instead.

Converting this PR to draft until we have some coverage to verify these changes.

[nfcampos]

Wonderful, this is much better.

What versions of node are you targeting?

the ideal way to use fetch is to 1. accept it as an argument (for unit tests) but default to looking for a global fetch function, which is now available in node 18+ and all other JS envs

[zeke]

What versions of node are you targeting?

We don't have a documented policy, but LTS (currently >=18)) seems sensible.

[nfcampos]

Great, then there is no reason to use cross-fetch, as fetch is available globally in node 18+ without a flag

[danielrhodes]

This is great. Was going to fork this library to use inside a Cloudflare Worker. They don't support node (so axios does not work), but they do support a browser-like fetch. I believe a similar issue would pop up if using this library inside an AWS Lambda Edge function or Vercel Edge functions.

[mattt]

Now that we're mocking HTTP responses with nock (#38), this is now ready for review.

[zeke]

🎉 cc @gr2m