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/0.1.619660%2Brev-63c3a29ca82437c87573e4c6919b09a24ea61b0f/018f3b26-5e03-7aa3-b783-09324dde70c2/source.tar.gz?narHash=sha256-4cPymbty65RvF1DWQfc%2BBc8B233A1BWxJnNULJKQ1EY%3D' (2024-05-02)