flake.lock: Update

Flake lock file updates:

• Updated input 'nixpkgs':
    'https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.1.533189%2Brev-87828a0e03d1418e848d3dd3f3014a632e4a4f64/018b0dc8-e84f-7c59-b5d6-16849c3b2074/source.tar.gz?narHash=sha256-YXUNI0kLEcI5g8lqGMb0nh67fY9f2YoJsILafh6zlMo%3D' (2023-10-06)
  → 'https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.1.581229%2Brev-f8e2ebd66d097614d51a56a755450d4ae1632df1/018d8a37-bd05-79cb-a42f-290c1f0ca0ce/source.tar.gz?narHash=sha256-2en1kvde3cJVc3ZnTy8QeD2oKcseLFjYPLKhIGDanQ0%3D' (2024-02-07)