fix parameter name in docstring (#21032)

src/transformers/pipelines/feature_extraction.py

@@ -44,7 +44,7 @@ class FeatureExtractionPipeline(Pipeline):
             If no framework is specified, will default to the one currently installed. If no framework is specified and
             both frameworks are installed, will default to the framework of the `model`, or to PyTorch if no model is
             provided.
-        return_tensor (`bool`, *optional*):
+        return_tensors (`bool`, *optional*):
             If `True`, returns a tensor according to the specified framework, otherwise returns a list.
         task (`str`, defaults to `""`):
             A task-identifier for the pipeline.