PyMI does not build on 3.13

```
      PyMI.cpp
      PyMI\PyMI.cpp(37): error C3861: 'PyEval_ThreadsInitialized': identifier not found
      PyMI\PyMI.cpp(39): warning C4996: 'PyEval_InitThreads': deprecated in 3.9
```

PyEval_ThreadsInitialized was deprecated in 3.9 and apparently removed in 3.12