Correct qt6-header-fixes check
Let check be applied to header files. Add list to ignore the Qt library header files triggering the checks. Those files get included from the included files in tests/qt6-header-fixes/main.cpp.
Let check be applied to header files. Add list to ignore the Qt library header files triggering the checks. Those files get included from the included files in tests/qt6-header-fixes/main.cpp.