find package also for Qt6 (#574)

fix linuxdeployqt makefile: use Qt${QT_VERSION_MAJOR} instead of Qt5

tools/linuxdeployqt/CMakeLists.txt

@@ -9,7 +9,7 @@ add_definitions("-DLINUXDEPLOYQT_GIT_COMMIT=\"${GIT_COMMIT}\"")
 add_definitions("-DBUILD_DATE=\"${DATE}\"")
 add_definitions("-DBUILD_NUMBER=\"${BUILD_NUMBER}\"")
 
-find_package(Qt5 REQUIRED COMPONENTS Core)
+find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Core)
 
 # update excludelist
 message(STATUS "Updating excludelist...")
@@ -26,5 +26,5 @@ mark_as_advanced(EXCLUDELIST EXCLUDELIST_RESULT)
 
 add_executable(linuxdeployqt main.cpp shared.cpp)
 target_include_directories(linuxdeployqt PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
-target_link_libraries(linuxdeployqt Qt5::Core)
+target_link_libraries(linuxdeployqt Qt${QT_VERSION_MAJOR}::Core)
 target_compile_definitions(linuxdeployqt PRIVATE -DEXCLUDELIST="${EXCLUDELIST}")