Limit number of checkpoint on `examples/pytorch/summarization/run_summarization.py` same as `save_total_limit` on `Trainer`
# 🚀 Feature request

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Is it possible to limit the amount of checkpoints created in `examples/pytorch/summarization/run_summarization.py`. I finetuned a model and it keeps on creating a new checkpoint every 5000 steps. I know this is already implemented in transformers `Trainer` as `save_total_limit`

## Motivation

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I finetuned my first model using Pegasus and the `run_summarization.py` script provided in the docs. I noticed that colab was always running out of memory so I had to manually delete checkpoints after every 1500 steps. This would make finetuning Pegasus models using `run_summarization.py` less tedious. 

## Your contribution

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I could implement the `save_total_limit` param in `run_summarization.py` if this is not yet implemented. Just need to look on how to do it.

Nevermind I think I figured it out. Looks like `run_summarization.py` inherits everything from `Trainer` so adding `--save_total_limit 2`  to the passed args limits the number of checkpoint savefiles. 