Python dependencies for 'downscaleR'

[miturbide]

@zequihg50 highlighted the following in issue #60:

Note however that downscaleR has several dependencies on python that need to be considered to be included in the package. See the scripts.

This applies to the isimip3 implementation for bias correction.

[cofinoa]

@miturbide where is being explained how to configure the python dependencies for the ISIMIP3 part?

Appears that someone already face this issue before:

SantanderMetGroup/downscaleR#82