[chore] flake.lock: update inputs

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/2527da1ef492c495d5391f3bcf9c1dd9f4514e32' (2024-08-24)
  → 'github:NixOS/nixpkgs/6e99f2a27d600612004fbd2c3282d614bfee6421' (2024-08-30)
• Updated input 'nixvim':
    'github:nix-community/nixvim/4814147442cd3f12f8160ecad9e36751f68cdc22' (2024-08-27)
  → 'github:nix-community/nixvim/caefb266bee301922a4cf4d4564b1b000a0a21c3' (2024-08-31)
• Updated input 'nixvim/git-hooks':
    'github:cachix/git-hooks.nix/c8a54057aae480c56e28ef3e14e4960628ac495b' (2024-08-23)
  → 'github:cachix/git-hooks.nix/4509ca64f1084e73bc7a721b20c669a8d4c5ebe6' (2024-08-28)
• Updated input 'nixvim/treefmt-nix':
    'github:numtide/treefmt-nix/070f834771efa715f3e74cd8ab93ecc96fabc951' (2024-08-22)
  → 'github:numtide/treefmt-nix/3ffd842a5f50f435d3e603312eefa4790db46af5' (2024-08-28)
• Updated input 'unstable':
    'github:NixOS/nixpkgs/d0e1602ddde669d5beb01aec49d71a51937ed7be' (2024-08-24)
  → 'github:NixOS/nixpkgs/71e91c409d1e654808b2621f28a327acfdad8dc2' (2024-08-28)