refactor: Use node:timers/promises/setTimeout (#190)

Refactoring to use `require('node:timers/promises').setTimeout` rather
than `require('util').promisify(setTimeout)`.

No need to promisify a function as there's a native promise version of
that: [Timers Promises
API](https://nodejs.org/api/timers.html#timerspromisessettimeoutdelay-value-options)

Author: mauriciolauffer

test/resources/concurrency/srv/concurrency.js

@@ -1,7 +1,6 @@
 
 const cds = require('@sap/cds')
-const util = require('util')
-const sleep = util.promisify(setTimeout)
+const sleep = require('node:timers/promises').setTimeout
 
 class ConcurrencyService extends cds.ApplicationService { init(){
 

test/resources/concurrency/srv/data-and-errors.js

@@ -1,7 +1,6 @@
 
 const cds = require('@sap/cds')
-const util = require('util')
-const sleep = util.promisify(setTimeout)
+const sleep = require('node:timers/promises').setTimeout
 
 class DataAndErrorsService extends cds.ApplicationService { init(){