misc/qt6ct: Bump after update Qt6 for rebuild package

qt6ct is still linked against Qt 6.7.x therefore it cannot work under
Qt 6.8.x. Just launching the app you get a prompt that says that it's
linked against an incompatible Qt version.

PR: 284012
Approved by: tcberner (maintainer, timeout > 5 months)
MFH: 2024Q2