Replace or remove java 6 module

[MiniDigger | Martin]

See PaperMC/Paper#2179

java 12 dropped support for java 6, so its not possible to compile paperclip with java 12+.
two options: either that module can be remove or should be bumped up to 7.

[Mark Vainomaa]

But muh legacy???

I think that's fine, most of the modern OS-es don't even offer Java 6 easily afaik.

[MiniDigger | Martin]

@mikroskeem, the only point of that module is to yell at ppl to install Java 8+ 😂
So if they manage to install Java 6 and we dropped that module, they get an obscure error message instead.

[Zach]

There’s a PR for this at GH-15

Will probably fast track that this weekend and get paper repos updated with a newer version