I think it'd be cleaner to have a "--lister" option that would let you set which lister you want to act on (and which would instantiate the proper lister once), then a createdb and a dropdb "action" that would do what's expected:

python3 -m swh.lister --lister gitlab --db-url postgresql:///lister-gitlab createdb
python3 -m swh.lister --lister github --db-url postgresql:///lister-github dropdb
...

On a related note, the actions should probably be called create-tables and drop-tables, as they really don't create databases, just populate them.