PET_py module should be added to cfe_py or added as a new repo to NWC-CUAHSI-SI

[RY4GIT]

This should reside in either of the cfe_py or a new repo in NWC-CUAHSI-SI
https://github.com/NWC-CUAHSI-Summer-Institute/data_assimilation_with_bmi/blob/cfe_pet/CFE_PET/fao_pet.py
https://github.com/NWC-CUAHSI-Summer-Institute/data_assimilation_with_bmi/blob/cfe_pet/CFE_PET/bmi_PET.py