TMSS-568: Adapt code to make t_subtasks and t_scheduling pass

...ices/tmss_postgres_listener/lib/tmss_postgres_listener.py

SAS/TMSS/backend/src/tmss/tmssapp/adapters/parset.py

SAS/TMSS/backend/src/tmss/tmssapp/adapters/sip.py

SAS/TMSS/backend/src/tmss/tmssapp/models/scheduling.py

SAS/TMSS/backend/src/tmss/tmssapp/subtasks.py

SAS/TMSS/backend/test/t_scheduling.py

SAS/TMSS/backend/test/t_subtasks.py

SAS/TMSS/backend/test/test_utils.py

SAS/TMSS/backend/test/tmss_test_data_django_models.py

SAS/TMSS/backend/test/tmss_test_data_rest.py