Adapt build system for building against qt6

CMakeLists.txt

@@ -49,7 +49,7 @@ set(KDEPIM_LIB_VERSION "${PIM_VERSION}")
 set(KDEPIM_LIB_SOVERSION "5")
 
 set(QT_REQUIRED_VERSION "5.15.2")
-find_package(Qt5 ${QT_REQUIRED_VERSION} CONFIG REQUIRED Widgets)
+find_package(Qt${QT_MAJOR_VERSION} ${QT_REQUIRED_VERSION} CONFIG REQUIRED Widgets)
 
 
 # Find KF5 package

konsolekalendar/CMakeLists.txt

@@ -34,7 +34,7 @@ ecm_qt_declare_logging_category(konsolekalendar
     )
 
 target_link_libraries(konsolekalendar
-    Qt::DBus
+    Qt${QT_MAJOR_VERSION}::DBus
     KF5::CalendarUtils
     KF5::CalendarCore
     KF5::CalendarSupport