Change unit test to match pull request result

Author: Anton Evers

app/code/Magento/Cron/Test/Unit/Observer/ProcessCronQueueObserverTest.php

@@ -660,7 +660,7 @@ public function testDispatchGenerate()
         $schedule->expects($this->any())->method('unsScheduleId')->willReturnSelf();
         $schedule->expects($this->any())->method('trySchedule')->willReturnSelf();
         $schedule->expects($this->any())->method('getCollection')->willReturn($this->_collection);
-        $schedule->expects($this->exactly(1))->method('save')->willReturnSelf();
+        $schedule->expects($this->atLeastOnce())->method('save')->willReturnSelf();
 
         $this->_collection->addItem(new \Magento\Framework\DataObject());
         $this->_collection->addItem($schedule);