Fix docstring in DagFileProcessor._schedule_task_instances (#8948)

airflow/jobs/scheduler_job.py

@@ -890,8 +890,8 @@ class DagFileProcessor(LoggingMixin):
 
         :param dagbag: DagBag
         :type dagbag: models.DagBag
-        :param ti_keys_to_schedule:  List of task instnace keys which can be scheduled.
-        :param ti_keys_to_schedule:
+        :param ti_keys_to_schedule: List of task instnace keys which can be scheduled.
+        :type ti_keys_to_schedule: list
         """
         # Refresh all task instances that will be scheduled
         TI = models.TaskInstance