Update dependencies

[github-actions]

Automated dependency update:

• Updated nixpkgs flake input
• Synced stack.yaml snapshot with nixpkgs LTS version
• Updated Cabal/Cabal-syntax to latest from Hackage
• Regenerated nix package definitions

[chreekat]

Aha, this one also got stuck because the workflow didn't run.

https://github.com/peter-evans/create-pull-request/blob/main/docs/concepts-guidelines.md#triggering-further-workflow-runs

I'll have to fix that soon.

[juhp]

Should dist-newstyle/cache/config be in the repo?