flake.lock: Update

Flake lock file updates:

• Updated input 'flake-parts':
    'github:hercules-ci/flake-parts/77826244401ea9de6e3bac47c2db46005e1f30b5?narHash=sha256-Tyw1RjYEsp5scoigs1384gIg6e0GoBVjms4aXFfRssQ%3D' (2025-07-01)
  → 'github:hercules-ci/flake-parts/644e0fc48951a860279da645ba77fe4a6e814c5e?narHash=sha256-TVcTNvOeWWk1DXljFxVRp%2BE0tzG1LhrVjOGGoMHuXio%3D' (2025-07-21)
• Updated input 'hercules-ci-agent':
    'github:hercules-ci/hercules-ci-agent/c9648a5a0ee1e7637a81a1961394c7dad87cd58e?narHash=sha256-8P%2BsTsAlFbQRSasrEs/FKrCdR5NpyX8JgYm%2B9iGHK/U%3D' (2025-07-18)
  → 'github:hercules-ci/hercules-ci-agent/f73aeae4663dbdcd93bd9ceba74a203c8e5c023d?narHash=sha256-PMxDBBgvu9e56Yx7/v6y/%2BMFqGZEAOduvSvxabf1fkQ%3D' (2025-07-22)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/147633ad35aba48f75af49be7ddc956c71c35acc?narHash=sha256-QznRD2YNqBVT%2BLjrV36rIuOZO1XKbjm1BgtMTIrTDVg%3D' (2025-07-20)
  → 'github:NixOS/nixpkgs/57ccc02c7fe9294deee037379a4a6378661cbab8?narHash=sha256-whYj15V9N5XJF3PMMzBY8axIFtHJxlomzggVmX%2BGliA%3D' (2025-07-24)

Author: hercules-ci[bot]