SummarizationPipeline: init required task name (#5086)

* SummarizationPipeline: init required task name

* Update src/transformers/pipelines.py

Co-authored-by: Sam Shleifer <sshleifer@gmail.com>

* Apply suggestions from code review

Co-authored-by: Sam Shleifer <sshleifer@gmail.com>

src/transformers/pipelines.py

@@ -1391,6 +1391,10 @@ class SummarizationPipeline(Pipeline):
             on the associated CUDA device id.
     """
 
+    def __init__(self, **kwargs):
+        kwargs.update(task="summarization")
+        super().__init__(**kwargs)
+
     def __call__(
         self, *documents, return_tensors=False, return_text=True, clean_up_tokenization_spaces=False, **generate_kwargs
     ):