moved temperature warper before topP/topK warpers
# What does this PR do?

Moves the `temperature` warper in `generation_utils.py` before `top_p` and `top_k` warper so that temperature affects sampling. This is how it used to be [before refactoring](https://github.com/huggingface/transformers/blob/v3.4.0/src/transformers/generation_utils.py#L571-L575) in `v.3.5.x`.

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [x] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
- [ ] 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.
- [ ] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/master/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/master/docs#writing-source-documentation).
- [ ] Did you write any new necessary tests?

@patrickvonplaten