fix cors

backend/index.js

@@ -1,10 +1,13 @@
 const express = require('express');
+const cors = require('cors');
 
 const port = 3001;
 const app = express();
 
 app.use(express.json());
 
+app.use(cors("*"));
+
 app.get("/test", async (req, res) => {
   res.send("Hello World!");
 });