fix: 8405 pattern serialization

[Smixi]

Change Summary

Added Pattern type for serialization and default schema values.

Related issue number

fix pydantic/pydantic#8405

Checklist

• Unit tests for the changes exist
• Documentation reflects the changes where applicable (I don't know if there is for other types).
• Pydantic tests pass with this pydantic-core (except for expected changes)
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @adriangb

[codecov]

Codecov Report

Merging #1168 (ce507bf) into main (4538190) will decrease coverage by 0.01%.
The diff coverage is 81.25%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1168      +/-   ##
==========================================
- Coverage   90.00%   89.99%   -0.01%     
==========================================
  Files         106      106              
  Lines       16656    16672      +16     
  Branches       36       36              
==========================================
+ Hits        14991    15004      +13     
- Misses       1658     1661       +3     
  Partials        7        7              

Files	Coverage Δ
src/serializers/infer.rs	95.12% <90.00%> (-0.12%)	⬇️
src/serializers/ob_type.rs	81.46% <66.66%> (-0.36%)	⬇️

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[codspeed-hq]

CodSpeed Performance Report

Merging #1168 will improve performances by 27.51%

_{Comparing Smixi:add-pattern-type (ce507bf) with main (4538190)}

Summary

⚡ 2 improvements
✅ 144 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	Smixi:add-pattern-type	Change
⚡	test_core_future	37.7 µs	29.6 µs	+27.51%
⚡	test_core_future_str	39.6 µs	31.6 µs	+25.21%

[Smixi]

please review

[davidhewitt]

This makes sense to me and is consistent with how similar implementations are done; let's merge 👍