Migrate metric to Evaluate in Pytorch examples (#18369)

* Migrate metric to Evaluate in pytorch examples

* Remove unused imports

examples/pytorch/summarization/run_summarization.py

@@ -27,8 +27,9 @@ from typing import Optional
 import datasets
 import nltk  # Here to have a nice missing dependency error message early on
 import numpy as np
-from datasets import load_dataset, load_metric
+from datasets import load_dataset
 
+import evaluate
 import transformers
 from filelock import FileLock
 from transformers import (
@@ -598,7 +599,7 @@ def main():
     )
 
     # Metric
-    metric = load_metric("rouge")
+    metric = evaluate.load("rouge")
 
     def postprocess_text(preds, labels):
         preds = [pred.strip() for pred in preds]