Multi-OS CI: add GHC 9.6, restrict to last 3 versions

Author: andreasabel

.github/workflows/haskell.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ghc: ['9.4.4', '9.2.5', '9.0.2', '8.10.7']
+        ghc: ['9.6.2', '9.4.5', '9.2.8']
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
     - uses: actions/checkout@v3
@@ -26,7 +26,7 @@ jobs:
       id:   setup
       with:
         ghc-version:   ${{ matrix.ghc }}
-        cabal-version: '3.8.1.0'
+        # cabal-version: '3.8.1.0'
         cabal-update:  true
 
     - name: Cache