0.20.0 doesn't build on ghc 9.4.2 about doctest

[sol]

#382 by @eddiejessup looks promising, but there's a possible space leak that needs investigation.

[eddiejessup]

Just a shout that #382 is now merged, so if the problems are now gone maybe we can close this issue?

[danwdart]

Looks like maybe a shim or a bit of CPP is required to switch between the new behaviour of some of these:

Strangely the first one wouldn't work on ghc 9.2 either:
https://hackage.haskell.org/package/ghc-9.0.2/docs/GHC-Runtime-Loader.html#v:initializePlugins
vs
https://hackage.haskell.org/package/ghc-9.2.4/docs/GHC-Runtime-Loader.html#v:initializePlugins
vs
https://hackage.haskell.org/package/ghc-9.4.2/docs/GHC-Runtime-Loader.html#v:initializePlugins

HDS now come in chunks:
https://hackage.haskell.org/package/ghc-9.2.4/docs/GHC-Hs-DocString.html#v:unpackHDS
vs
https://hackage.haskell.org/package/ghc-9.4.2/docs/GHC-Hs-DocString.html#v:unpackHDSC

I also see that there are several PRs in progress:

#382
#379
#376
#375

so I'll be doing my testing on one of those, so awesome job, folks.

[danwdart]

Thanks - I see 0.20.1 in Hackage, I'll put it through my pipeline tonight and make sure I can build it with no issues.

[ysangkok]

@danwdart Did it work? Builds fine for me.

[danwdart]

Seems great to me. Nix may have forgotten to remove the check though... I'm just letting them know.