Fix username argument for pg_dump
Fix username argument for pg_dump

Correct parameter according to the pg_dump documentation: https://www.postgresql.org/docs/9.6/static/app-pgdump.html

Getting error with `--user`:
pg_dump: too many command-line arguments (first is "--host=127.0.0.1")

django-dbbackup/django-dbbackup,django-dbbackup/django-dbbackup,ZuluPro/django-dbbackup,ZuluPro/django-dbbackup,mjs7231/django-dbbackup,mjs7231/django-dbbackup