feat: update flake.lock (#97)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/20075955deac2583bb12f07151c2df830ef346b4?narHash=sha256-HMwfAJBdrr8wXAkbGhtcby1zGFvs%2BStOp19xNsbqdOg%3D' (2025-08-19)
  → 'github:nixos/nixpkgs/d7600c775f877cd87b4f5a831c28aa94137377aa?narHash=sha256-tlOn88coG5fzdyqz6R93SQL5Gpq%2Bm/DsWpekNFhqPQk%3D' (2025-08-30)

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Author: github-actions[bot]