feat: update nix flake

[Pitometsu-GeniusYield]

Clean up nix build configuration.

[rmgaray]

I'm afraid this PR no longer builds on my end:

error:
       … while evaluating the attribute 'shell'
         at /nix/store/3bnh2b6zls9sdmmnz4lprqmqwd563pq5-source/overlays/haskell.nix:851:13:
          850|             # Default shell
          851|             shell = shellFor rawProject.args.shell;
             |             ^
          852|

       … while evaluating the attribute 'hsPkgs.shellFor'
         at /nix/store/3bnh2b6zls9sdmmnz4lprqmqwd563pq5-source/overlays/haskell.nix:695:44:
          694|               project = addProjectAndPackageAttrs rec {
          695|                   inherit (pkg-set.config) hsPkgs;
             |                                            ^
          696|                   inherit pkg-set;

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: mismatch in field 'narHash' of input '{"__final":true,"lastModified":1739645821,"narHash":"sha256-HjAchUMLsiScm8Jyd+I/5YJKUjDp1r+XFzr05d+o+r4=","owner":"IntersectMBO","repo":"cardano-haskell-packages","rev":"045875beec586ff57a7333c0563fd5c2b1a308fa","type":"github"}', got '{"__final":true,"lastModified":1739645821,"narHash":"sha256-dmLSu2SvSaTDjSE03cU6DwY62J3nWJbVhIn/kKtMwJg=","owner":"IntersectMBO","repo":"cardano-haskell-packages","rev":"045875beec586ff57a7333c0563fd5c2b1a308fa","type":"github"}'

However, if I update the lock file it succeeds. I'm interested in having this merged (mostly because of issue #450), is there anything else holding this back?

[sourabhxyz]

@rmgaray Thank you for your response, PR is now merged.

[rmgaray]

Thank you!