remove hidden psycopg2 dependency

[gkennos]

this is an implicit dependency because of copy_expert call

orm-loader/src/orm_loader/loaders/loading_helpers.py

Line 206 in 786f817

cur.copy_expert(

[gkennos]

relevant updated docs: https://www.psycopg.org/psycopg3/docs/basic/copy.html#copy