+ Prefer GHC 8.10.7 to 8.10.4, as versions seem to have stabilised now.
+ Add support for Stackage LTS 19, which ships with GHC 9.0.2.
+ Since a new version of 9.2 has been released, prefer 9.2.2 over 9.2.1.
Also, explicitly pass -XCPP to hlint; see [1].
[1]: https://github.com/ndmitchell/hlint/issues/1360
Building xmonad-contrib benefits greatly from compiling modules in
parallel. Vanessa McHale suggested setting ghc-options in
xmonad-contrib.cabal in #431, but that's bad practice—these options
should be set by the user/environment where it's being built, not
selfishly hardcoded for specific package. In stack.yaml and
cabal.haskell-ci, we know for sure that xmonad-contrib is the terminal
(leaf) library, so we can set it there and speed up builds in our CI and
also for anyone who uses our stack.yaml (not that anyone should).
Closes: https://github.com/xmonad/xmonad-contrib/pull/431
