BUG: Fix some index_col tests for pyarrow read_csv
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit) for how to run them
- [ ] whatsnew entry

add this PR number on the same release note for the arrow reader > add this PR number on the same release note for the arrow reader

This shouldn't be necessary, as its unreleased. I'm planning a lot more changes to the Arrow CSV reader to bring up somewhat up to par, and this would add clutter to the release notes. > > add this PR number on the same release note for the arrow reader
> 
> This shouldn't be necessary, as its unreleased. I'm planning a lot more changes to the Arrow CSV reader to bring up somewhat up to par, and this would add clutter to the release notes.

it doesn't matter. the arrow change is now composed of multiple PRs which is totally fine (an alternative if you want is to link these follow PRs to the original at the top). The point is in theory we can point to a single issue / PR to have the full change. thanks @lithomas1 