Fix RegExp UTF-16 Matching

The crate used to evaluate regexp, [regress](https://github.com/ridiculousfish/regress), fixed the [utf-16 matching problems](https://github.com/kaleidawave/ezno/issues/184#issuecomment-2274383051) in their [0.10.3 release](https://github.com/ridiculousfish/regress/releases/tag/v0.10.3). The `RegExp::exec` function now correctly matches using utf-16 instead of utf-8. ### Before (`main`):  ### After (`regexp-utf16`):  ### Expected: