This Merge

This PR is the regular merge of the haskell-updates branch into master.

This branch is being continually built and tested by hydra at https://hydra.nixos.org/jobset/nixpkgs/haskell-updates.

I will aim to merge this PR by 2021-07-12. If I can merge it earlier, there might be successor PRs in that time window. As part of our rotation @cdepillabout will continue these merges from 2021-07-12 to 2021-07-26

haskellPackages Workflow Summary

Our workflow is currently described in
pkgs/development/haskell-modules/HACKING.md.

The short version is this:

• We regularly update the Stackage and Hackage pins on haskell-updates (normally at the beginning of a merge window).
• The community fixes builds of Haskell packages on that branch.
• We aim at at least one merge of haskell-updates into master every two weeks.
• We only do the merge if the mergeable job is succeeding on hydra.
• If a maintained package is still broken at the time of merge, we will only merge if the maintainer has been pinged 7 days in advance. (If you care about a Haskell package, become a maintainer!)

This is the follow-up to #127833