Add additional finetuned model checkpoints to model loading

[anuragg1209]

Motivation and Context

Added finetuned checkpoints

Public API Changes

• No Public API changes
• Yes, Public API changes (Details below)

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How Has This Been Tested?

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Checklist

• The changes have been tested locally.
• Documentation has been updated (if the public API or usage changes).
• A entry has been added to CHANGELOG.md (if relevant for users).
• The code follows the project's style guidelines.
• I have considered the impact of these changes on the public API.

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[Copilot]

Pull Request Overview

This PR adds additional finetuned model checkpoints to the TabPFN v2 classifier model loading functionality. The change expands the available model variants by including 5 new finetuned checkpoint files.

• Adds 5 new finetuned model checkpoint filenames to the classifier list
• Maintains consistency with existing checkpoint naming convention
• Extends model availability without changing the core loading mechanism

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[gemini-code-assist]

Code Review

This pull request adds several new finetuned model checkpoints. My review focuses on improving the maintainability of the model list, which is growing with these additions. I've suggested restructuring and sorting the list of model filenames to make it more readable and easier to manage in the future.