chore: make a port configurable by PORT env variable

Author: php-coder

src/templates/app.js.ejs

@@ -24,6 +24,7 @@ app.get('<%- endpoint.path %>', (req, res) => {
 })
 <% }); %>
 
-app.listen(3000, () => {
-    console.log('Listen on 3000')
+const port = process.env.PORT || 3000;
+app.listen(port, () => {
+    console.log(`Listen on ${port}`)
 })