Move configuration to pytest hook.

pytest_django_testing_postgresql.py

 from dj_database_url import parse
 from django.conf import settings
+import pytest
 from testing.postgresql import Postgresql
 
-_postgresql = Postgresql()
 
-django.settings.DATABASES['default'] = parse(_postgresql.url())
+@pytest.hookimpl(tryfirst=True)
+def pytest_load_initial_conftests(early_config, parser, args):
+    _postgresql = Postgresql()
+    settings.configure(DATABASES={'default': parse(_postgresql.url())})