Added missing import

src/models/RunnerTeam.ts

@@ -1,5 +1,5 @@
 import { Entity, Column, ManyToOne, ChildEntity } from "typeorm";
-import { IsOptional } from "class-validator";
+import { IsNotEmpty } from "class-validator";
 import { RunnerGroup } from "./RunnerGroup";
 import { RunnerOrganisation } from "./RunnerOrganisation";