To resolve this remove the semi-colon in your argument.
CALL WORKORDERPACKAGE.CreateWorkOrder('20200722','Leak Survey 3 Year','{"Area": "Map 49", "ScheduledStartDate": "12/31/2019", "ScheduledFinishDate": "7/31/2020", "Assignments": ["AllWorkers"], "FieldValues": {"PROJECT_NAME": "0318_TestWO_009", "WorkOrderComment": "", "WorkOrderEquipment": [""]}}',1)
Also add a commitTransaction()
sql_conn = arcpy.ArcSDESQLExecute(<sde connectionfile path>)
sql = 'CALL <packagename>.<procedure name>(<parameters>)'
success = sql_conn.execute(sql)
if success:
sql_conn.commitTransaction()