heroes: remove unused import

Author: petebacondarwin

tour-of-heroes/src/app/dashboard.component/dashboard.component.shallow.spec.ts

@@ -2,7 +2,6 @@ import { TestBed, async, fakeAsync, tick } from '@angular/core/testing';
 import { NO_ERRORS_SCHEMA } from '@angular/core';
 import { DashboardComponent } from './dashboard.component';
 import { Router } from '@angular/router';
-import { RouterTestingModule } from '@angular/router/testing';
 import { HeroService } from '../hero.service/hero.service';
 import { ExponentialStrengthPipe } from '../exponential-strength.pipe/exponential-strength.pipe';