Log Message:
grantlee-qt5: update to 5.3.1

* Use C++11 nullptr where appropriate
* Use QRandomGenerator instead of deprecated qRand
* Increase compatibility with Qt 6 APIs
* Add CMake option to build with Qt 6 - GRANTLEE_BUILD_WITH_QT6
* Support enum introspection on Q_GADGET
* filesizeformat implementation as well as localized filesize
* Make enums comparable with more operations
* Add "truncatechars" filter
* Fix concatenation of string lists