flake: update inputs

[github-actions[bot]]

Automated changes by the update-flake-lock GitHub Action.

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/fd16bb6d3bcca96039b11aa52038fafeb6e4f4be?narHash=sha256-LJbHQQ5aX1LVth2ST%2BKkse/DRzgxlVhTL1rxthvyhZc%3D' (2024-04-20)
  → 'github:NixOS/nixpkgs/d6f6eb2a984f2ba9a366c31e4d36d65465683450?narHash=sha256-Yg5D5LhyAZvd3DZrQQfJAVK8K3TkUYKooFtH1ulM0mw%3D' (2024-04-27)

Running GitHub Actions on this PR

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To run GitHub Actions workflows on this PR, run:

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