flake.lock: Update (#101)

Automated changes by the
[update-flake-lock](https://github.com/DeterminateSystems/update-flake-lock)
GitHub Action.

```
Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/8f3e1f807051e32d8c95cd12b9b421623850a34d?narHash=sha256-/qlNWm/IEVVH7GfgAIyP6EsVZI6zjAx1cV5zNyrs%2BrI%3D' (2025-01-04)
  → 'github:NixOS/nixpkgs/5df43628fdf08d642be8ba5b3625a6c70731c19c?narHash=sha256-Tbk1MZbtV2s5aG%2BiM99U8FqwxU/YNArMcWAv6clcsBc%3D' (2025-01-16)
```

### Running GitHub Actions on this PR

GitHub Actions will not run workflows on pull requests which are opened
by a GitHub Action.

To run GitHub Actions workflows on this PR, run:

```sh
git branch -D update_flake_lock_action
git fetch origin
git checkout update_flake_lock_action
git commit --amend --no-edit
git push origin update_flake_lock_action --force
```

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: floxbot