add casefold comparison to the repeated tools usage check

[arylwen]

Some open-source models, e.g., mixtral, would generate the same tool call with a different case. With a casefold comparison, we could reduce the number of repeated tool calls.

[github-actions[bot]]

This PR is stale because it has been open for 45 days with no activity.

[pythonbyte]

Hey @arylwen!

Thanks for the pull request!

Could you take a moment to check if the changes are still relevant and working properly? If you could share a few examples, that would really help me test your use case. I appreciate your help, and just let me know if there's anything we can do to help.

[bhancockio]

Closed due to inactivity.