fix(queue): change _jobScheduler from private to protected for extension (#2920)

Author: roggervalf

src/classes/index.ts

@@ -5,6 +5,7 @@ export * from './child-processor';
 export * from './errors';
 export * from './flow-producer';
 export * from './job';
+export * from './job-scheduler';
 // export * from './main'; this file must not be exported
 // export * from './main-worker'; this file must not be exported
 export * from './queue-base';

src/classes/queue.ts

@@ -153,7 +153,7 @@ export class Queue<
   protected libName = 'bullmq';
 
   private _repeat?: Repeat; // To be deprecated in v6 in favor of JobScheduler
-  private _jobScheduler?: JobScheduler;
+  protected _jobScheduler?: JobScheduler;
 
   constructor(
     name: string,