Update app.js

Addint module export for serverless function working

app.js

@@ -0,0 +1,27 @@
+const express = require('express');
+
+const app = express()
+const PORT = 8000
+
+app.get('/', (req, res) => {
+  res.send('Hello World')
+})
+
+app.get('/about', (req, res) => {
+  res.send('About route 🎉 ')
+})
+
+const start = () => {
+    try {
+        const port = process.env.PORT || 3000;
+        app.listen(port, () =>
+            console.log(`✅ Server is listening on port ${port}.........`)
+        );
+    } catch (err) {
+        console.error('Failed to start server:', err);
+    }
+};
+
+start();
+
+module.exports = app;