Update pytorch_lightning/utilities/distributed.py

Co-authored-by: ananthsub <[email protected]>

Author: kaushikb11

pytorch_lightning/utilities/distributed.py

@@ -315,7 +315,7 @@ def register_ddp_comm_hook(
     )
 
 
-def tpu_distributed():
+def tpu_distributed() -> bool:
     if _TPU_AVAILABLE:
         return xm.xrt_world_size() > 1
     return False