build(deps): bump nixpkgs-unstable from d233902 to f9d8b65

Bumps [nixpkgs-unstable](https://github.com/NixOS/nixpkgs) from `d233902` to `f9d8b65`.
- [Commits](NixOS/nixpkgs@d233902...f9d8b65)

---
updated-dependencies:
- dependency-name: nixpkgs-unstable
  dependency-version: f9d8b65950353691ab56561e7c73d2e1063d810b
  dependency-type: direct:production
...

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Author: dependabot[bot]