Hackage Version Bump

[RiugaBachi]

I noticed that the master branch of lambdacube-ir builds just fine under cabal and GHC 8.6.5. I assume the reason this hasn't been version bumped on Hackage yet is due to the fact that lambdacube-compiler builds fail under the same conditions due to megaparsec-0.7 compatibility issues.

That said, should #21 be merged - and assuming lambdacube-ir will also be bumped on Hackage simultaneously -, lambdacube-compiler will be able to be built under cabal and modern versions of GHC. It would be long due for a version bump at this point, I believe.