Call PyEval_InitThreads() with PyPy for Python 3.9
In theory it should no longer be needed, but PyPy hasn't updated this part of their implementation yet, and not initing threads will lead to crashes due to missing GIL init.
In theory it should no longer be needed, but PyPy hasn't updated this part of their implementation yet, and not initing threads will lead to crashes due to missing GIL init.