Update for Python 3.12 and Numpy 2.0

[alexfikl]

This updates the code to work with the latest versions:

• Python 3.12 removed the imp module used in pyweno.version. I removed this entirely and just imported the other files.
• Numpy 2.0 removed PyArray_DOUBLE in favor of NPY_DOUBLE.
• Numpy 2.3 also removed NPY_IN_ARRAY in favor of NPY_ARRAY_IN_ARRAY.

This builds locally and the tests run without any errors.