changed logic in index.ts

backend/src/index.ts

 import express, {Express, Request, Response} from 'express';
 import {linksRouter} from './routes/links.router';
 import {collections, connectToDatabase} from './services/database.service';
+import cors from 'cors';
 
 const app: Express = express();
 app.use(express.json());
+app.use(cors());
 app.use('/links', linksRouter);
 
 connectToDatabase()