feat: update flake.lock (#90)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/5c724ed1388e53cc231ed98330a60eb2f7be4be3?narHash=sha256-xVNy/XopSfIG9c46nRmPaKfH1Gn/56vQ8%2B%2BxWA8itO4%3D' (2025-07-04)
  → 'github:nixos/nixpkgs/9807714d6944a957c2e036f84b0ff8caf9930bc0?narHash=sha256-LwWRsENAZJKUdD3SpLluwDmdXY9F45ZEgCb0X%2BxgOL0%3D' (2025-07-08)

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Author: github-actions[bot]