@GrahamcOfBorg build haskellPackages.shh

@maralorn Thanks for sending this PR.

Two things:

• The correct branch is actually release-20.03 (not nixos-20.03). I realize this is confusing, and it seems like everyone is making this mistake recently.
• You'll have to directly edit the pkgs/development/haskell-modules/hackage-packages.nix file and remove the broken = true; and hydraPlatforms = []; lines for shh. The process for doing this is different from the haskell-updates branch. It is not automated on the release branches.

* The correct branch is actually `release-20.03` (not `nixos-20.03`).  I realize this is confusing, and it seems like everyone is making this mistake recently.

I know that.^^ I just forgot.

* You'll have to directly edit the `pkgs/development/haskell-modules/hackage-packages.nix` file and remove the `broken = true;` and `hydraPlatforms = [];` lines for `shh`.  The process for doing this is different from the `haskell-updates` branch.  It is not automated on the release branches.

Well I already did that in #88719 . But I didn‘t realize at that time, that the tests are broken on hydra, that‘s why I unbroke a broken package.

@maralorn Aahhh, sorry, I understand what happened.

Okay, this looks good, merging in. Thanks for backporting this.