Qt6: Update to 6.6.0

Qt 6.6.0 is a feature release with focus on improving UX capabilities
including responsive UI technology and the Qt Graph module.

The Qt Coap module has been added as net/qt6-coap. [1]

PySide6 and PyQt6 have also been updated to 6.6.0.

Announcement: https://www.qt.io/blog/qt-6.6-released
Rel note: https://code.qt.io/cgit/qt/qtreleasenotes.git/about/qt/6.6.0/release-note.md

PR:		275068, 274911 [1]
MFH:		2023Q4
Exp-run by:	antoine