feat: remove our dependency on undici

[erunion]

🧰 Changes

While pulling our latest release of this library into our main app I was having a lot of problems with Webpack trying to compile in undici into our frontend code because of the logic we've got here if the File API isn't present. Well much to my surprise Node began exposing this back in 18.13.0¹.

By removing undici completely and using File in node:buffer folks who use Webpack (especially api users) will be able to add a fallback for it²:

resolve: {
  fallback: {
    buffer: require.resolve('buffer/')
  }
}

Though this requires pinning our minimum Node 18 release at 18.13.0 instead of just 18.* I'm iffy on considering this a breaking change because Node 18.13.0 was released by in January and everyone, including us, who are using 18 should be past it by now. We may want to also pin @readme/api-core and api to >=18.13.0 though because they, well at least api-core, use this library.

Footnotes

1. https://github.com/nodejs/node/blob/main/doc/changelogs/CHANGELOG_V18.md#2023-01-05-version-18130-hydrogen-lts-danielleadams ↩

2. Something they've likely already had to do for the Blob polyfill we are using out of it if global.Blob isn't present. ↩