Implemented update function in cache_utils.py, with a test file test_cache_utils.py
Author: ailunc
Pull request: yes

# What does this PR do?
Implemented update function in cache_utils.py, with a test file test_cache_utils.py
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Fixes # (issue)https://github.com/huggingface/transformers/issues/37078

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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      Pull Request section?
- [x] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case. https://github.com/huggingface/transformers/issues/37078
- [x] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
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