Update installs in image classification doc (#29947)

Trainer with PyTorch now requires accelerate to be installed.

Partly resolves huggingface/transformers#29174

docs/source/en/tasks/image_classification.md

@@ -43,7 +43,7 @@ The task illustrated in this tutorial is supported by the following model archit
 Before you begin, make sure you have all the necessary libraries installed:
 
 ```bash
-pip install transformers datasets evaluate
+pip install transformers datasets evaluate accelerate
 ```
 
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