Updates to use latest ghc-9.6 & 9.8 point releases

This isn't actively used in haskell.nix; however, it's common to
exchange the roles of 8.10.7 and the 9.6 release in the list of flake
variants there. In lieu of explicitly using 9.6.5, using nix' ghc96
alias for the latest point release of 9.6 makes sense to avoid needing
to churn the codebase at each such release. Similar applies to 9.8
within haskell.yml. github-page.yml also needs updating to work with
the changed variant name for building haddock documentation.

.github/workflows/github-page.yml

@@ -31,17 +31,17 @@ jobs:
 
     - name: Fetch nix cache and update cabal indices
       run: |
-        nix develop .\#project.x86_64-linux.projectVariants.ghc964.shell --command \
+        nix develop .\#project.x86_64-linux.projectVariants.ghc96.shell --command \
           cabal update
 
     - name: Build whole project
       run: |
-        nix develop .\#project.x86_64-linux.projectVariants.ghc964.shell --command \
+        nix develop .\#project.x86_64-linux.projectVariants.ghc96.shell --command \
           cabal build all
 
     - name: Build documentation
       run: |
-        nix develop .\#project.x86_64-linux.projectVariants.ghc964.shell --command \
+        nix develop .\#project.x86_64-linux.projectVariants.ghc96.shell --command \
           cabal haddock-project --local --output=./haddocks --internal --foreign-libraries
 
     - name: Compress haddocks

.github/workflows/haskell.yml

@@ -26,15 +26,15 @@ jobs:
       fail-fast: false
       matrix:
         # If you edit these versions, make sure the version in the lonely macos-latest job below is updated accordingly
-        ghc: ["9.6.4", "9.8.1"]
+        ghc: ["9.6", "9.8"]
         cabal: ["3.10.2.1"]
         os: [windows-latest, ubuntu-latest]
         include:
           # Using include, to make sure there will only be one macOS job, even if the matrix gets expanded later on.
           # We want a single job, because macOS runners are scarce.
           - os: macos-latest
             cabal: "3.10.2.1"
-            ghc: "9.6.4"
+            ghc: "9.6"
 
     env:
       # Modify this value to "invalidate" the cabal cache.

nix/haskell.nix

@@ -22,7 +22,7 @@ let
       name = "cardano-node";
       compiler-nix-name = lib.mkDefault "ghc8107";
       # extra-compilers
-      flake.variants = lib.genAttrs ["ghc964"] (x: {compiler-nix-name = x;});
+      flake.variants = lib.genAttrs ["ghc96"] (x: {compiler-nix-name = x;});
       cabalProjectLocal = ''
         repository cardano-haskell-packages-local
           url: file:${CHaP}