Remove @borsboom maintainership

[borsboom]

I haven't actively used Haskell in some time and am not really able to usefully respond to maintenance requirements for these packages. Is there a way to find someone to take them over?

---

Checklist:

• Meaningful commit message, eg add my-cool-package (please don't mention build-constraints.yml)
• At least 30 minutes have passed since uploading to Hackage
• If applicable, required system libraries are added to 02-apt-get-install.sh or 03-custom-install.sh
• (optional) Package is compatible with the latest version of all dependencies (Run cabal update && cabal outdated)
• (optional) Package have been verified to work with the latest nightly snapshot, e.g by running the verify-package script

The script runs virtually the following commands in a clean directory:

  stack unpack $package-$version # `-$version` is optional
  cd $package-$version
  rm -f stack.yaml && stack init --resolver nightly --ignore-subdirs
  stack build --resolver nightly --haddock --test --bench --no-run-benchmarks

[juhp]

@borsboom could you please move the packages to the Grandfathered or the Unmaintained section instead.
We don't like to remove packages from Stackage "just because", thanks

[borsboom]

@juhp Thanks for telling me about the "Grandfathered dependencies" section; I didn't know about that. I've moved the packages there (except for stack which I moved to @mpilgrem's section).