[Misc] Auto-reformat multiple python folders. (#5325)

* auto-reformat

* lintrunner

---------
Co-authored-by: Ubuntu <ubuntu@ip-172-31-28-63.ap-northeast-1.compute.internal>

tutorials/multi/1_graph_classification.py

@@ -71,7 +71,8 @@ process ID, which should be an integer from `0` to `world_size - 1`.
 """
 
 import os
-os.environ['DGLBACKEND'] = 'pytorch'
+
+os.environ["DGLBACKEND"] = "pytorch"
 import torch.distributed as dist