Stop supporting GHC-8.4.4

[harendra-kumar]

We have stopped supporting ghc-8.4.4 in streamly, can drop support here as well.

[pranaysashank]

what does dropping support mean? People who want to use will still have an old version to fall back onto, right?

[harendra-kumar]

It means new versions of fusion-plugin cannot be used for old compilers. We will remove the code so that maintenance is easier. Basically, remove any CPP macros specific to that version.