deps: update simdutf to 5.6.0

PR-URL: nodejs#55379
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Yagiz Nizipli <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>

Author: nodejs-github-bot