Upgrade to GHC 9.6.3

[enobayram]

We're upgrading to GHC 9.6.3 because that's what chainweb-node currently uses, so that we can reuse the same /nix/store paths for our Haskell toolchain.

[enobayram]

I've verified this PR by running it as the chainweb-data service of the sandbox using the following command:

nix run --impure \
  --override-input chainweb-data github:kadena-io/chainweb-data/enis/ghc-963 \
  github:kadena-io/devnet#container-default

This started a local sandbox, so I've visited localhost:8080 and:

• Performed a successful chainweb-data-fill operation.
• Verified in the explorer that all the pages using CW-D as the backend work:
  • Event search
  • Transaction search
  • Transfers view
  • Txdetail view

[enobayram]

This PR is encountering build issues with cabal on MacOS even though nix build works. The build issues are caused by pact and its transitive dependencies, so I'll hold this PR until we merge #186, which removes pact as a dependency.