flake.lock: Update

Flake lock file updates:

• Updated input 'flake-parts':
    'github:hercules-ci/flake-parts/f4330d22f1c5d2ba72d3d22df5597d123fdb60a9?narHash=sha256-%2Bu2UunDA4Cl5Fci3m7S643HzKmIDAe%2BfiXrLqYsR2fs%3D' (2025-03-07)
  → 'github:hercules-ci/flake-parts/c621e8422220273271f52058f618c94e405bb0f5?narHash=sha256-hIshGgKZCgWh6AYJpJmRgFdR3WUbkY04o82X05xqQiY%3D' (2025-04-01)
• Updated input 'nixpkgs':
    'git+https://github.com/NixOS/nixpkgs?ref=nixos-unstable-small&rev=8b1bcd4edc0de0a950eb117a37c55294997588b5&shallow=1' (2025-03-27)
  → 'git+https://github.com/NixOS/nixpkgs?ref=nixos-unstable-small&rev=06f3516b0397bd241bde2daefc8538fc886c5467&shallow=1' (2025-04-05)
• Updated input 'treefmt-nix':
    'github:numtide/treefmt-nix/29a3d7b768c70addce17af0869f6e2bd8f5be4b7?narHash=sha256-WRAylyYptt6OX5eCEBWyTwOEqEtD6zt33rlUkr6u3cE%3D' (2025-03-27)
  → 'github:numtide/treefmt-nix/815e4121d6a5d504c0f96e5be2dd7f871e4fd99d?narHash=sha256-uhjnlaVTWo5iD3LXics1rp9gaKgDRQj6660%2BgbUU3cE%3D' (2025-04-04)

Author: github-actions[bot]