chore(deps): bump nixpkgs from f4b6996 to 391b592

Bumps [nixpkgs](https://github.com/nixos/nixpkgs) from `f4b6996` to `391b592`.
- [Commits](NixOS/nixpkgs@f4b6996...391b592)

---
updated-dependencies:
- dependency-name: nixpkgs
  dependency-version: 391b592eb44808b3bd0cb80bb71b63a5a118b8bb
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]