Update to 1.20

[calliecameron]

Ideally 1.20.1, since it's the most widely-used version.

There already a bug for 1.21 at #22, but since lots of mods haven't updated past 1.20 yet, 1.20 would also be convenient for use in modpacks.

[Virus5600]

I'll consider this one. Though, it might take me more time if ever I decided to work on this one due to how lacking the documentations are on the API itself.