Upgrade to PyO3 0.23

[davidhewitt]

PyO3 0.23 contains some breaking changes & perf changes, want to check these briefly against jiter & core...

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 32 lines in your changes missing coverage. Please review.

Project coverage is 88.90%. Comparing base (1fbdb1e) to head (53622f1).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/jiter/src/value.rs	41.17%	13 Missing and 7 partials ⚠️
crates/jiter/src/python.rs	61.53%	3 Missing and 7 partials ⚠️
crates/jiter/src/number_decoder.rs	0.00%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #137      +/-   ##
==========================================
- Coverage   91.09%   88.90%   -2.19%     
==========================================
  Files          13       13              
  Lines        2145     2191      +46     
  Branches     2145     2191      +46     
==========================================
- Hits         1954     1948       -6     
- Misses        109      148      +39     
- Partials       82       95      +13     

Files with missing lines	Coverage Δ
crates/jiter/src/py_lossless_float.rs	84.90% <100.00%> (+1.26%)	⬆️
crates/jiter/src/py_string_cache.rs	97.05% <100.00%> (ø)
crates/jiter/src/number_decoder.rs	88.73% <0.00%> (-2.76%)	⬇️
crates/jiter/src/python.rs	90.86% <61.53%> (-3.17%)	⬇️
crates/jiter/src/value.rs	81.10% <41.17%> (-7.00%)	⬇️

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[codspeed-hq]

CodSpeed Performance Report

Merging #137 will improve performances by 10.24%

_{Comparing dh/pyo3-0.23 (53622f1) with main (1fbdb1e)}

Summary

⚡ 1 improvements
✅ 72 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	dh/pyo3-0.23	Change
⚡	unicode_jiter_value	9.5 µs	8.6 µs	+10.24%