Adds dep for ordering pytest tests.

apps/cic-ussd/test_requirements.txt

@@ -5,6 +5,7 @@ pytest-alembic==0.2.5
 pytest-celery==0.0.0a1
 pytest-cov==2.10.1
 pytest-mock==3.3.1
+pytest-ordering==0.6
 pytest-redis==2.0.0
 requests-mock==1.8.0
 tavern==1.14.2