Add support for Cabal 3.6

[ivb-supercede]

Cabal 3.6 introduced a breaking change where many FilePaths were replaced with SymbolicPaths - this adds in a compatibility layer for that change.

[yav]

Thanks @ivb-supercede ! I don't remember if the 8.2.2 and 8.0.2 builds were failing before, would mind having a look?

[ivb-supercede]

Doh! Yep, that's a break I introduced. I'll have to un-nest the definition of the compatibility layer so it's not under Cabal 2.2+

[jumper149]

Some time has passed...

I personally think it's fine to accept the backwards-incompatible change at this point.

---

I think I ran into this issue right here: https://github.com/jumper149/homepage/actions/runs/3064171134/jobs/4947026997#step:4:1776

[ivb-supercede]

Whoops, thanks for reminding me about this PR. The backwards-compatibility issue should be fixed now.

[jumper149]

Hmm, I tried using this branch.

Now this happens:

[3 of 5] Compiling Graphmod.CabalSupport ( src/Graphmod/CabalSupport.hs, dist/build/Graphmod/CabalSupport.o, dist/build/Graphmod/CabalSupport.dyn_o )

src/Graphmod/CabalSupport.hs:53:1: error:
    parse error on input ‘import’
   |
53 | import Distribution.Utils.Path (SymbolicPath, PackageDir, SourceDir, getSymbolicPath)

I guess it works on CI, because it's using an older cabal version.