fix(milestones): enforce valid status transitions with state machine …#199

AnoukRImola wants to merge 2 commits intoDisciplr-Org:mainDisciplr-Org/Disciplr-backend:mainfrom

AnoukRImola:task/milestones-transitionsAnoukRImola/Disciplr-backend:task/milestones-transitionsCopy head branch name to clipboard