fix: use spec'ed formdata

[jimmywarting]

This PR remove the dependency of form-data package

FormData exists built in to NodeJS now in v18+ now.
Both got and node-fetch support encoding a spec'ed FormData themself now, and the form-data package is now considered as legacy by node-fetch and gots standards. form-data haven't been updated for a long while and it lacks many methods and don't really follow the specification.

node-fetch ships with a polyfilled FormData and ways to get Blob/File like objects backed up by the filesystem that is read lazily when needed (thanks to the fetch-blob package). The native FormData provided by NodeJS themself do also support Blob / File like objects and dosen't need to be strictly the same instances of globalThis.Blob so node-fetch can now also export the native FormData when it's available.

---

This might be a little bit of topic but i think you should strive towards eventually being able to replace node-fetch and got with built in features provided by NodeJS themself to have fewer dependencies. a long term goal and a granular replacement would be to:

• Switch out got for node-fetch
• Switch out node-fetch for Undici when dropping support for NodeJS v16.8
• Switch out Undici for built in Fetch when dropping support for NodeJS v18
• Switch out fetch-blob/from.js for native fn when NodeJS adds a feature to get blob/files backed up by the file system

[webpro]

Thanks @jimmywarting, it's in v15.6.0.

Totally agree with your suggestions, will keep it in mind.