chore: Chroma - pin tokenizers

[anakin87]

Related Issues

• Chroma tests on python 3.8 are failing due to missing tokenizers: https://github.com/deepset-ai/haystack-core-integrations/actions/runs/12060032349/job/33629714424
• this happens because the latest version of tokenizers does not have binaries for python 3.8 (see [BLD] Bound tokenizers version chroma-core/chroma#3202)

Proposed Changes:

• pin tokenizers, as they do in [BUG] Bound tokenizers, patch CVP test chroma-core/chroma#3211

How did you test it?

CI

Notes for the reviewer

• the pin will be removed as soon as Chroma releases a new version where they adopt the pin themselves
• (in general, we should think about when to discontinue python 3.8 compatibility)

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.

[shadeMe]

LGTM. Can we open a tracking issue for reverting this change?

[anakin87]

I created the issue to revert this change: #1225.