added helmet for security

src/app.js

@@ -2,10 +2,12 @@ const express = require('express');
 const cors = require('cors');
 const { logger, requestLogger } = require('./util/logger');
 const routes = require('./routes');
+const helmet = require('helmet');
 
 const app = express();
 
 app.use(cors());
+app.use(helmet());
 app.use(express.json());
 app.use(express.urlencoded({ extended: true }));