Don't allow Qt6 for color widget yet (#2230)

external/Qt-Color-Widgets/CMakeLists.txt

@@ -44,7 +44,7 @@ SET (${COLORWIDGET_PROJECT_NAME}_VERSION "${${COLORWIDGET_PROJECT_NAME}_VERSION_
 
 
 set(QT_VERSION_MAJOR 5)
-find_package(QT NAMES Qt5 Qt6 Qt4 COMPONENTS Core QUIET)
+find_package(QT NAMES Qt5 Qt4 COMPONENTS Core QUIET)
 find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Core Widgets REQUIRED)