flake.lock: Update (#136)

Flake lock file updates:

• Updated input 'flake-utils':
    'github:numtide/flake-utils/ff7b65b44d01cf9ba6a71320833626af21126384' (2023-09-12)
  → 'github:numtide/flake-utils/4022d587cbbfd70fe950c1e2083a02621806a725' (2023-12-04)
• Updated input 'neovim-nightly':
    'github:neovim/neovim/5651c1ff27a1eb59d120637ba5cbd90f08a3f1d2?dir=contrib' (2023-12-03)
  → 'github:neovim/neovim/3159a2c28f5ea8797cb525c74dedd622bfe4a0a1?dir=contrib' (2023-12-05)

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