flake.lock: Update (#68)

Flake lock file updates:

• Updated input 'neovim-nightly':
    'github:neovim/neovim/bb38c066a96512cf8cb2ef2e733494b5bbdfa3fd?dir=contrib' (2023-09-09)
  → 'github:neovim/neovim/2b475cb5cc2196a32085fbbdfd7357cbb02a1cb0?dir=contrib' (2023-09-11)
• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/b200e0df08f80c32974a6108ce431d8a8a5e6547' (2023-09-07)
  → 'github:nixos/nixpkgs/78058d810644f5ed276804ce7ea9e82d92bee293' (2023-09-10)
• Updated input 'pre-commit-hooks':
    'github:cachix/pre-commit-hooks.nix/7e3517c03d46159fdbf8c0e5c97f82d5d4b0c8fa' (2023-08-17)
  → 'github:cachix/pre-commit-hooks.nix/4f883a76282bc28eb952570afc3d8a1bf6f481d7' (2023-09-10)

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