Bump CI Mac Cache

[EncodePanda]

Should we continue maintaining the Mac OS in CI? It's the second time I'm bumping it this week

[jaspervdj]

@EncodePanda I don't have strong feelings about having Mac OS in CI, but I know some people are using the release binaries for Mac OS. And, well, if we don't build Mac OS on each run, it can be a bit stressful if it turns out it's broken right before a release.

We could look into other options for the CI though, I think https://github.com/haskell/actions has been gaining some traction, or we could use hashFiles on the cabal/stack files to avoid the manual version bumps?

[EncodePanda]

@jaspervdj There maybe could also be value in just relying on nix to build stylish. I think there are github actions allowing you to install Nix. We could then rely on caching mechanism (from IOHK's hydra to get the right GHC and from cachix as well - they have some plans for open source projects).