Asking if necromancy is still being practiced in the “ modern” world, is like asking if people still worship Gods in the “ modern” world.
Magic have always and will always be practiced, by those who feel connected to it. The number of the people who practice magic may decrease or increase over time, but still Magic and all it’s paths will be practiced, for at least thousands years to come.
Why ? You must dwell into the realm of the unknown, to understand the reason.