Support for GHC 9.8

[Vekhir]

@bergmark
When building fclabels 2.0.5.1 using GHC 9.8 on Arch, the following error occurs:

[ 6 of 10] Compiling Data.Label.Derive ( src/Data/Label/Derive.hs, dist/build/Data/Label/Derive.dyn_o )

src/Data/Label/Derive.hs:310:55: error: [GHC-83865]
    • Couldn't match type ‘BndrVis’ with ‘()’
      Expected: [TyVarBndr ()]
        Actual: [TyVarBndr BndrVis]
    • In the fourth argument of ‘generateLabel’, namely ‘vars’
      In the second argument of ‘($)’, namely
        ‘generateLabel failing concrete name vars cons’
      In a stmt of a 'do' block:
        forM fields $ generateLabel failing concrete name vars cons
    |
310 |     forM fields $ generateLabel failing concrete name vars cons
    |                                                       ^^^^

This issue looks similar to linear-generics/linear-generics#25
The offending line is src/Data/Label/Derive.hs#L310

What do you think?

-- Vekhir