ghc: update livecheck
ghc: update livecheck

Since we have a `ghc@9` formula now, livecheck picks up false version
updates for ghc.

Before:

    ❯ brew livecheck ghc
    ghc : 8.10.4 ==> 9.0.1

After:

    ❯ brew livecheck ghc
    ghc : 8.10.4 ==> 8.10.4
dsXLII/homebrew-core,mfikes/homebrew-core,adam-moss/homebrew-core,Linuxbrew/homebrew-core,filcab/homebrew-core,sjackman/homebrew-core,zyedidia/homebrew-core,mbcoguno/homebrew-core,Moisan/homebrew-core,uyjulian/homebrew-core,spaam/homebrew-core,stgraber/homebrew-core,lemzwerg/homebrew-core,Moisan/homebrew-core,cblecker/homebrew-core,makigumo/homebrew-core,filcab/homebrew-core,sjackman/homebrew-core,nbari/homebrew-core,makigumo/homebrew-core,JCount/homebrew-core,Linuxbrew/homebrew-core,stgraber/homebrew-core,nandub/homebrew-core,zyedidia/homebrew-core,spaam/homebrew-core,adam-moss/homebrew-core,chrisfinazzo/homebrew-core,mfikes/homebrew-core,lemzwerg/homebrew-core,Homebrew/homebrew-core,mbcoguno/homebrew-core,chrisfinazzo/homebrew-core,JCount/homebrew-core,nbari/homebrew-core,nandub/homebrew-core,Homebrew/homebrew-core,mbcoguno/homebrew-core,dsXLII/homebrew-core,cblecker/homebrew-core,uyjulian/homebrew-core