Allow sip import in newer versions of PyQt5

modules/gui/pymod/__init__.py

modules/gui/pymod/export_input.cc

modules/gui/pymod/init_context_menu.py

modules/gui/pymod/init_menubar.py

modules/gui/pymod/scene/file_loader.py

modules/gui/pymod/scene/init_inspector.py

modules/gui/pymod/scene/inspector_widget.py

modules/gui/pymod/scene/scene_selection_helper.py

modules/gui/pymod/sip_handler.hh