doula/tests/test_push.py: Remove unused `import ipdb` - hopefully gets
rid of IPython warning on Mac
Eliminate warning about deprecated `sets` module
doula/tests/test_service_config_dal.py: Fix error: "AttributeError:
'ServiceConfigDAL' object has no attribute '_get_latest_service_config'"
Fix failure: doula.tests.test_release.ReleaseTests