Explicitly stop postgres test database.

pytest_django_testing_postgresql.py

@@ -12,3 +12,6 @@ _POSTGRESQL = Postgresql()
 def pytest_load_initial_conftests(early_config, parser, args):
     os.environ['DJANGO_SETTINGS_MODULE'] = early_config.getini('DJANGO_SETTINGS_MODULE')
     settings.DATABASES['default'] = parse(_POSTGRESQL.url())
+
+def pytest_unconfigure(config):
+    _POSTGRESQL.stop()