Fix integer background job id type error

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

lib/private/BackgroundJob/JobList.php

@@ -273,7 +273,7 @@ class JobList implements IJobList {
 				}
 			}
 
-			$job->setId($row['id']);
+			$job->setId((int) $row['id']);
 			$job->setLastRun($row['last_run']);
 			$job->setArgument(json_decode($row['argument'], true));
 			return $job;