flake.lock: Update (#579)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/7bb2ccd8cdc44c91edba16c48d2c8f331fb3d856' (2024-04-25)
  → 'github:nixos/nixpkgs/63c3a29ca82437c87573e4c6919b09a24ea61b0f' (2024-05-02)
• Updated input 'pre-commit-hooks':
    'github:cachix/pre-commit-hooks.nix/6fb82e44254d6a0ece014ec423cb62d92435336f' (2024-04-24)
  → 'github:cachix/pre-commit-hooks.nix/2849da033884f54822af194400f8dff435ada242' (2024-04-30)
• Updated input 'rust-overlay':
    'github:oxalica/rust-overlay/2a42c742ab04b61d9b2f1edf392842cf9f27ebfd' (2024-04-26)
  → 'github:oxalica/rust-overlay/b37d96b614c38922674fd8d81ebc2fe807667a5b' (2024-05-04)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>