fix tag error in item sprints doing the opposite of what it should.

usecases/sprints/service.go

@@ -215,7 +215,7 @@ func (s *Service) Create(ctx context.Context, sprint entities.Sprint, parts []en
 				}
 			}
 
-			if len(sprint.Tags) == 0 {
+			if len(sprint.Tags) > 0 {
 				return nil, models.BadInputError{
 					Object:  "SprintInput",
 					Field:   "tags",