sort completed workouts by date

iphone/Werkout_ios/subview/CompletedWorkoutsView.swift

@@ -58,7 +58,9 @@ struct CompletedWorkoutsView: View {
         CompletedWorkoutFetchable().fetch(completion: { result in
             switch result {
             case .success(let model):
-                completedWorkouts = model
+                completedWorkouts = model.sorted(by: {
+                    $0.createdAt > $1.createdAt
+                })
             case .failure(let failure):
                 fatalError(failure.localizedDescription)
             }