Fix #69, remove any columns in the filter when their types are datetime.
Fix #69, remove any columns in the filter when their types are datetime.

mxlei01/healthcareai-py,HealthCatalyst/healthcareai-py,jpo/healthcareai-py,HealthCatalystSLC/healthcareai-py,HealthCatalyst/healthcareai-py,HealthCatalystSLC/healthcareai-py,jpo/healthcareai-py,mxlei01/healthcareai-py