flake.inputs: automatic update

Flake lock file updates:

• Updated input 'agenix':
    'github:ryantm/agenix/572baca9b0c592f71982fca0790db4ce311e3c75' (2023-09-15)
  → 'github:ryantm/agenix/1f677b3e161d3bdbfd08a939e8f25de2568e0ef4' (2023-09-22)
• Updated input 'home-manager':
    'github:nix-community/home-manager/9787dffff5d315c9593d3f9fb0f9bf2097e1b57b' (2023-09-11)
  → 'github:nix-community/home-manager/07682fff75d41f18327a871088d20af2710d4744' (2023-09-19)
• Updated input 'nix-index-database':
    'github:Mic92/nix-index-database/9d2bcc47110b3b6217dfebd6761ba20bc78aedf2' (2023-09-17)
  → 'github:Mic92/nix-index-database/25d6369c232bbea1ec1f90226fd17982e7a0a647' (2023-09-24)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/5d017a8822e0907fb96f7700a319f9fe2434de02' (2023-09-17)
  → 'github:NixOS/nixpkgs/715d72e967ec1dd5ecc71290ee072bcaf5181ed6' (2023-09-22)
• Updated input 'unstable':
    'github:NixOS/nixpkgs/5148520bfab61f99fd25fb9ff7bfbb50dad3c9db' (2023-09-17)
  → 'github:NixOS/nixpkgs/e12483116b3b51a185a33a272bf351e357ba9a99' (2023-09-21)