Qt5::WebEngine doesn't exist in qt6 and it's not necessary for qt5 build

CMakeLists.txt

@@ -65,7 +65,7 @@ set(QT_REQUIRED_VERSION "5.15.2")
 option(KDEPIM_ENTERPRISE_BUILD "Enable features specific to the enterprise branch, which are normally disabled. Also, it disables many components not needed for Kontact such as the Kolab client." FALSE)
 
 
-find_package(Qt${QT_MAJOR_VERSION} ${QT_REQUIRED_VERSION} CONFIG REQUIRED DBus Network Test Widgets WebEngine WebEngineWidgets)
+find_package(Qt${QT_MAJOR_VERSION} ${QT_REQUIRED_VERSION} CONFIG REQUIRED DBus Network Test Widgets WebEngineWidgets)
 set(LIBGRAVATAR_VERSION "5.19.40")
 set(MAILCOMMON_LIB_VERSION "5.19.42")
 set(MESSAGELIB_LIB_VERSION "5.19.40")