Added import to database documentation sample code

Author: pzarfos

docs/database.rst

@@ -370,6 +370,8 @@ Put this into ``conftest.py``::
 
     @pytest.fixture(scope='session')
     def django_db_setup():
+        from django.conf import settings
+
         settings.DATABASES['default'] = {
             'ENGINE': 'django.db.backends.mysql',
             'HOST': 'db.example.com',