Replace // operator with / operator + long() (#13013)

src/transformers/generation_utils.py

@@ -1835,7 +1835,7 @@ class GenerationMixin:
                 next_token_scores, 2 * num_beams, dim=1, largest=True, sorted=True
             )
 
-            next_indices = next_tokens // vocab_size
+            next_indices = (next_tokens / vocab_size).long()
             next_tokens = next_tokens % vocab_size
 
             # stateless