deps: update simdutf to 5.6.0

PR-URL: nodejs#55379
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

Author: nodejs-github-bot