[Fixed]-Conditional Categories in Django

This problem often called “dependent select”

One of the packages solves this – https://github.com/runekaagaard/django-admin-flexselect

remove Sub_Specialization it is redundant

use django-mptt https://django-mptt.github.io/django-mptt/models.html#setting-up-a-django-model-for-mptt

and django-mptt-admin https://github.com/mbraak/django-mptt-admin