Copy WithJsonSchema schema to avoid sharing mutated data

[thejcannon]

Change Summary

Quick-and-simple. Just .copy() the return self.json_schema inside of WithJsonSchema so that other parts of the pipeline that modify the schema don't modify the shared object.

Related issue number

Fix #11013

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @sydney-runkle

[codspeed]

CodSpeed Performance Report

Merging #11014 will not alter performance

_{Comparing thejcannon:patch-1 (1da5638) with main (6f31f8f)}

Summary

✅ 46 untouched benchmarks

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
pydantic
json_schema.py
Project Total

This report was generated by python-coverage-comment-action

[thejcannon]

please review (and thank you ❤️ )

[sydney-runkle]

@Viicos and I discussed this. Happy to accept this fix for now. We think a shallow copy is appropriate, though if any other issues are raised related to this, we could consider a deepcopy instead.

Thanks for your contribution!