Create list of classes that have changed since last release

[ramonawalls]

Write code that produces a file with four colunns:

|Current CURIE|Current label|Previous CURIE|Previous label|

where Previous CURIE and Previous label are only displayed when there is a change.

Make it part of the makefile if possible.

This file will then be used in the data ingest pipeline to identify any changes that need to be made to mappings. TODO: create a corresponding issue in https://github.com/Phenobase/phenobase_data/issues.