Changed world_size() to get_world_size() bugfix (#22381)

Edited one line in src/transormers/generation/utils.py. Changed dist.world_size() to dist.get_world_size() since world_size() doesn't exist in pytorch.dist.

src/transformers/generation/utils.py

@@ -1193,7 +1193,7 @@ class GenerationMixin:
         """
 
         if synced_gpus is None:
-            if is_deepspeed_zero3_enabled() and dist.world_size() > 1:
+            if is_deepspeed_zero3_enabled() and dist.get_world_size() > 1:
                 synced_gpus = True
             else:
                 synced_gpus = False