Add scheduled task subscriber entity and repository

[MAILPOET-2898]

lib/Newsletter/Sending/ScheduledTaskSubscribersRepository.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace MailPoet\Newsletter\Sending;
+
+use MailPoet\Doctrine\Repository;
+use MailPoet\Entities\ScheduledTaskSubscriberEntity;
+
+/**
+ * @extends Repository<ScheduledTaskSubscriberEntity>
+ */
+class ScheduledTaskSubscribersRepository extends Repository {
+  protected function getEntityClassName() {
+    return ScheduledTaskSubscriberEntity::class;
+  }
+}