chore(deps): bump nixpkgs from 2fad6ea to 68d8aa3 (#21651)

Bumps [nixpkgs](https://github.com/NixOS/nixpkgs) from `2fad6ea` to `68d8aa3`.
- [Commits](NixOS/nixpkgs@2fad6ea...68d8aa3)

---
updated-dependencies:
- dependency-name: nixpkgs
  dependency-version: 68d8aa3d661f0e6bd5862291b5bb263b2a6595c9
  dependency-type: direct:production
...

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