Add support for Unicode 17

This is preliminary, all tests pass, but needs more careful review.

Author: kovidgoyal

docs/changelog.rst

@@ -174,6 +174,8 @@ Detailed list of changes
 
 - Wayland: Fix ``center-sized`` panels not working on smithay based compositors (:pull:`9117`)
 
+- Add support for Unicode 17
+
 0.43.1 [2025-10-01]
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