Fix type hints (#1427)

vllm/core/scheduler.py

@@ -275,7 +275,7 @@ class Scheduler:
         # Create input data structures.
         seq_group_metadata_list: List[SequenceGroupMetadata] = []
         for seq_group in scheduler_outputs.scheduled_seq_groups:
-            seq_data: Dict[int, List[SequenceData]] = {}
+            seq_data: Dict[int, SequenceData] = {}
             block_tables: Dict[int, List[int]] = {}
             for seq in seq_group.get_seqs(status=SequenceStatus.RUNNING):
                 seq_id = seq.seq_id