flake.lock: Update

Flake lock file updates:

• Updated input 'fenix':
    'github:nix-community/fenix/dfaf3a97fe595a18bf9d55cda3416c17fe906f0f' (2023-11-08)
  → 'github:nix-community/fenix/28dbd8b43ea328ee708f7da538c63e03d5ed93c8' (2024-02-03)
• Updated input 'fenix/rust-analyzer-src':
    'github:rust-lang/rust-analyzer/3b7c7f97e4a7bb253a8d398ee4f8346f6cf2817b' (2023-11-07)
  → 'github:rust-lang/rust-analyzer/8f6a72871ec87ed53cfe43a09fb284168a284e7e' (2024-02-02)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/ec750fd01963ab6b20ee1f0cb488754e8036d89d' (2023-11-07)
  → 'github:NixOS/nixpkgs/442d407992384ed9c0e6d352de75b69079904e4e' (2024-02-09)
• Updated input 'utils':
    'github:numtide/flake-utils/ff7b65b44d01cf9ba6a71320833626af21126384' (2023-09-12)
  → 'github:numtide/flake-utils/1ef2e671c3b0c19053962c07dbda38332dcebf26' (2024-01-15)