using mkl in m_spectrum_ph3.py

[kmilo9999]

          I am not sure if this works at all. And apparently this is stuff that is done at the environment level when installing numpy, not within code. Further, often intel numpy (which is built with `mkl`) seems to be marginally faster, at best, than openBlast (standard) numpy (see https://stackoverflow.com/questions/69986869/how-to-enable-and-disable-intel-mkl-in-numpy-python and https://stackoverflow.com/questions/49992243/is-numpymkl-faster-than-numpy).

Originally posted by @cpaniaguam in #131 (comment)