Drop Support for ghc-8.0

[chitrak7]

Yesterday, GHC has dropped support for GHC-8.0. I think we should do it also.
I believe only affected dependency will be base.
Refer to commit:
152055a19cf368439c8450040b68142f8e7d0346

[snowleopard]

@chitrak7 Thanks! Yes, we'll need to switch to a later GHC and update our CI infrastructure.

However, let's postpone this until we have a working build, as #523 is still not fully resolved.

[izgzhen]

we updated the CI script to 8.2+ now, is there anything left to be done?

[alpmestan]

I personally don't think so. The configure script errors out with a proper error message if one's trying to use a incompatible boot ghc.

[snowleopard]

OK, let me close this.