cmake: Relax minimum required Qt version to support Ubuntu 24.04

This changes the minimum required Qt6 version from 6.9.0 to 6.4.0 to
ensure compatibility with Ubuntu 24.04, which ships with Qt 6.4.2.

Author: jcfr

CMakeLists.txt

@@ -20,7 +20,7 @@ endif()
 
 # Requirements
 set(minimum_required_qt5_version "5.15.0")
-set(minimum_required_qt6_version "6.9.0")
+set(minimum_required_qt6_version "6.4.0")
 set(minimum_required_qt_version ${minimum_required_qt${PythonQt_QT_VERSION}_version})
 
 find_package(Qt${PythonQt_QT_VERSION} ${minimum_required_qt_version} QUIET)

generator/CMakeLists.txt

@@ -18,7 +18,7 @@ if(NOT "${PythonQtGenerator_QT_VERSION}" MATCHES "^(5|6)$")
 endif()
 
 set(minimum_required_qt5_version "5.15.0")
-set(minimum_required_qt6_version "6.9.0")
+set(minimum_required_qt6_version "6.4.0")
 set(minimum_required_qt_version ${minimum_required_qt${PythonQtGenerator_QT_VERSION}_version})
 
 set(qt_required_components Core Xml)