Adapt to latest libunicode, making use of new grapheme_line_segmenter API #6700

Job	Run time
Check PR-TODOs	5s
Check CI scripts	3s
Check C++ style	29s
Check clang-tidy	14m 3s
Check links	10s
Fedora 39 linux/amd64 x86_64	11m 8s
Check editorconfig	4s
Archlinux ${{ matrix.arch }}	0s
FreeBSD 13	0s
macOS	5m 58s
Packaging for AppImage	5m 30s
Packaging for Ubuntu 20.04	5m 27s
Packaging for Ubuntu 22.04	5m 54s
Ubuntu Linux 22.04 (GCC 10, C++20, Qt6)	4m 27s
Windows	14m 35s
Ubuntu Linux 22.04 (Clang 15, C++20, Qt6)	3m 58s
Build notcurses (20.04)	3m 43s
Check Release	0s
Build notcurses (22.04)	3m 59s
Run tests via valgrind	0s
Run bench-headless	0s
Ubuntu Linux 22.04 post-check	1s
Check packages for Ubuntu	0s
GUI: notcurses-demo ${{ matrix.name }}	0s
GUI: Quick Shell Exit	0s
tests matrix	1s
Create Github release	0s
	1h 19m 35s

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