Update 23_day_event_listeners.md

Changed keyCode to key. keyCode is deprecated and key is used instead

23_Day_Event_listeners/23_day_event_listeners.md

@@ -304,7 +304,7 @@ We can access all the key numbers of the keyboard using different event listener
 
     <script>
       document.body.addEventListener('keypress', e => {
-        alert(e.keyCode)
+        alert(e.key)
       })
     </script>
   </body>