Fatal Python error when loading a nanobind extension built using free threaded python

python 3.13 (free threaded experimental build)
nanobind = 2.7.0
Windows 10
MSVC

When loading an extension, an error is thrown:
```
Fatal Python error: PyInterpreterState_Get: the function must be called with the GIL held, after Python initialization and before Python finalization, but the GIL is released (the current Python thread state is NULL)
Python runtime state: unknown
```