chore: update flake.lock

[mrcjkb]

Automated changes by the update-flake-lock GitHub Action.

Flake lock file updates:

• Updated input 'neovim-nightly':
    'github:neovim/neovim/2d33a766a17b7304686fc00eec2b2e0ce49400ba?dir=contrib' (2023-12-12)
  → 'github:neovim/neovim/d65c6a0bafada059e87a11a4bcd129afc16d2e5d?dir=contrib' (2023-12-12)

Running GitHub Actions on this PR

GitHub Actions will not run workflows on pull requests which are opened by a GitHub Action.

To run GitHub Actions workflows on this PR, run:

git branch -D update_flake_lock_action
git fetch origin
git checkout update_flake_lock_action
git commit --amend --no-edit
git push origin update_flake_lock_action --force