Fix rox-node fetch() return type (#40153)

types/rox-node/index.d.ts

@@ -92,7 +92,7 @@ export function setDynamicCustomPropertyRule(
  *
  * https://support.rollout.io/docs/nodejs-api#section-fetch
  */
-export function fetch(): Promise<unknown>;
+export function fetch(): void;
 
 /**
  * Creates a new Flag

types/rox-node/rox-node-tests.ts

@@ -22,6 +22,8 @@ Rox.setup('ROLLOUT_IO_KEY', {
   configurationFetchedHandler,
 }).then(linkTargetGroupAttributes);
 
+Rox.fetch();
+
 Rox.dynamicApi.isEnabled('system.repotAnalytics', false);
 Rox.dynamicApi.value('ui.textColor', 'red');