Ensure GIL before calling PyType_Ready(...)
When building with Python 3 and VTK_PYTHON_FULL_THREADSAFE enabled we need to ensure we have the GIL locked before calling PyType_Ready(...)
When building with Python 3 and VTK_PYTHON_FULL_THREADSAFE enabled we need to ensure we have the GIL locked before calling PyType_Ready(...)