docs(deps): Update dependency versions and add security note for pyda…

[justindobbs]

…ntic-ai SSRF fix

• Update pydantic-ai requirement from >=0.0.3,<1.0 to >=1.66.0,<2.0 in pyproject.toml
• Update openai-agents requirement from >=0.0.9 to >=0.10.4 in pyproject.toml
• Add SSRF fix note to pydantic_poc extra description in README
• Update pydantic_poc.md documentation to reflect new pydantic-ai>=1.66.0 requirement
• Add explicit shell=False to subprocess.run in maintainer.py for security clarity

Summary

• What problem does this PR solve?
• How does it solve it (major bullets)?

Testing

• python -m pytest
• python -m ruff check agent_bench
• Additional targeted tests (list):

Checklist

• Spec/docs updated (README, SPEC_FREEZE, changelog, etc., as needed)
• New tasks/tests added to registry + SPEC if applicable
• Roadmap items tracked in appropriate boards (if applicable)
• Security/privacy review (if touching telemetry, signing, or bundles)
• Verified CI status once pushed