ghc-8.4.4.nix: Do not use git.haskell.org
which was deprecated in 2018 and is now gone for good. I guess many
won’t notice because the nix-cache kept the files around?
(cherry picked from commit
b872b8a2009d68636fce8e4078dc9e65a70547fe and 29ca177c684cb42f0ea57171be5653b9b5060ba7)
authored by