devel/libunistring: Update 1.3 => 1.4

Changelog:

• The data tables and algorithms have been updated to Unicode version 17.0.0.
• Fixed a bug: The functions u*_grapheme_next and u*_grapheme_prev did not work right for strings with Indic characters, Emojis, or regional indicators.

Release notes:
https://savannah.gnu.org/news/?id=10818

PR: 289899