Fix the regex in `get_imports` to support multiline try blocks and excepts with specific exception types
# What does this PR do?
Fixes the regex in `get_imports` to support multiline try blocks and excepts with specific exception types, by
1. adding `re.DOTALL` so that new lines are matched in the try block
2. adding `.*?` after the except so that it will match things like `except ImportError`

Fixes #23667


## Before submitting
- [x] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#start-contributing-pull-requests),
      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.
- [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).
- [x] Did you write any new necessary tests?


## Who can review?
@sgugger 

_The documentation is not available anymore as the PR was closed or merged._<|||||>Done!