Fix buildHaskellPackages and CI for lts/ghc-9.6.x
Fix buildHaskellPackages and CI configuration for lts/ghc-9.6.x.
Changes
- Use correct buildHaskellPackages for GHC 9.6.x
- Update CI to use remote gitlab-ci include like horizon-ghc
Details
- Replaces manual CI stages with remote include from gitlab-ci 0.3.0
- Ensures buildHaskellPackages matches the GHC version