Fixup github pages CI with proper GHC version

Author: aniketd

.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.ghc96.shell --command \
+        nix develop --command \
           cabal update
 
     - name: Build whole project
       run: |
-        nix develop .\#project.x86_64-linux.projectVariants.ghc96.shell --command \
+        nix develop --command \
           cabal build all
 
     - name: Build documentation
       run: |
-        nix develop .\#project.x86_64-linux.projectVariants.ghc96.shell --command \
+        nix develop --command \
           cabal haddock-project --local --output=./haddocks --internal --foreign-libraries
 
     - name: Compress haddocks