Prepare 1.6.10 release

[CyMule]

Summary

• Add a 1.6.10 changelog entry for Python 3.13 support
• Bump unstructured_inference.__version__ to 1.6.10

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Note

Low Risk
Low risk release metadata update only: bumps the library version and adds a changelog entry; no runtime logic changes.

Overview
Prepares the 1.6.10 release by adding a 1.6.10 entry to CHANGELOG.md noting Python 3.13 support.

Bumps unstructured_inference.__version__ from 1.6.9 to 1.6.10.

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