flake.lock: Update

Flake lock file updates:

• Updated input 'fenix':
    'github:nix-community/fenix/24002092be13b2efe87700229d143b0d1eaa5d12' (2024-03-09)
  → 'github:nix-community/fenix/d3121c162a1fa4fabcb9af9642d50e8b05ddfe83' (2024-07-20)
• Updated input 'fenix/rust-analyzer-src':
    'github:rust-lang/rust-analyzer/2397e7a887252aa995d3790164b34b6c76ed94b4' (2024-03-08)
  → 'github:rust-lang/rust-analyzer/b333f85a9dc06a45d9eb126c6371414c49b46784' (2024-07-19)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/0e7f98a5f30166cbed344569426850b21e4091d4' (2024-03-09)
  → 'github:NixOS/nixpkgs/6e14bbce7bea6c4efd7adfa88a40dac750d80100' (2024-07-20)
• Updated input 'utils':
    'github:numtide/flake-utils/d465f4819400de7c8d874d50b982301f28a84605' (2024-02-28)
  → 'github:numtide/flake-utils/b1d9ab70662946ef0850d488da1c9019f3a9752a' (2024-03-11)