Support `unix-2.8.0.0`

[mitchellwrosen]

I've opened #62 as one solution, and there's an alternative solution here #60

[andreasabel]

@jacobstanley Supporting unix-2.8 becomes more relevant now that GHC 9.6 alpha is out which bundles unix-2.8.0.0.

[ysangkok]

@mitchellwrosen , FYI you're listed on the maintainers list now

[mitchellwrosen]

Yep! Release forthcoming. We're deciding where to house the new repo since I don't have write access to this one.

[mitchellwrosen]

Done in https://github.com/haskell-pkg-janitors/unix-compat and released to Hackage as unix-compat-0.7