flake.lock: Update

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/46397778ef1f73414b03ed553a3368f0e7e33c2f' (2024-05-22)
  → 'github:NixOS/nixpkgs/752c634c09ceb50c45e751f8791cb45cb3d46c9e' (2024-06-15)
• Updated input 'poetry2nix':
    'github:nix-community/poetry2nix/9ca8b7ccd9665c30a3cb47ce64cf47649404e093' (2024-05-26)
  → 'github:nix-community/poetry2nix/48e7ed4ef7832efa5a5558e573986c4128fc478f' (2024-06-18)
• Updated input 'poetry2nix/treefmt-nix':
    'github:numtide/treefmt-nix/2fba33a182602b9d49f0b2440513e5ee091d838b' (2024-05-17)
  → 'github:numtide/treefmt-nix/68eb1dc333ce82d0ab0c0357363ea17c31ea1f81' (2024-06-16)