Clear Dependabot high alert (pyo3)

[thomasrockhu-codecov]

Summary

• Bump pyo3 to 0.29.x to clear GHSA-36hh-v3qg-5jq4.
• Migrate custom FromPyObject impls to the 0.29 extract(Borrowed) API.

Test plan

• cargo check / CI passes
• Confirm Dependabot high clears after merge

[codecov]

Codecov Report

❌ Patch coverage is 90.19608% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.90%. Comparing base (b942e35) to head (c637590).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/junit.rs	80.00%	3 Missing ⚠️
src/testrun.rs	94.44%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #96      +/-   ##
==========================================
- Coverage   94.96%   94.90%   -0.07%     
==========================================
  Files          17       17              
  Lines        2087     2099      +12     
==========================================
+ Hits         1982     1992      +10     
- Misses        105      107       +2     

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[codecov-notifications]

Codecov Report

❌ Patch coverage is 90.19608% with 5 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/junit.rs	80.00%	3 Missing ⚠️
src/testrun.rs	94.44%	2 Missing ⚠️

📢 Thoughts on this report? Let us know!

[codspeed-hq]

Merging this PR will not alter performance

✅ 6 untouched benchmarks

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_{Comparing th/cve-pyo3 (c637590) with main (b942e35)}