Remove needless uses of PyString::intern

[davidhewitt]

Change Summary

While working on #1085 I noticed that we have some calls to PyString::intern in the validator build step. This isn't great; it's plain and simple a memory leak because:

• These strings are already held onto by the validators, no need to intern them
• Interning them means they will outlive the validators if they're destroyed

It's only a very minor issue, as validator build normally happens only on startup, but still worth cleaning up.

Related issue number

N/A

Checklist

• Unit tests for the changes exist
• Documentation reflects the changes where applicable
• 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: @dmontagu

[codecov]

Codecov Report

Merging #1088 (5dc764e) into main (be9c21c) will decrease coverage by 0.01%.
Report is 2 commits behind head on main.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1088      +/-   ##
==========================================
- Coverage   89.62%   89.62%   -0.01%     
==========================================
  Files         106      106              
  Lines       16366    16363       -3     
  Branches       35       35              
==========================================
- Hits        14668    14665       -3     
  Misses       1691     1691              
  Partials        7        7              

Files	Coverage Δ
src/lookup_key.rs	92.69% <100.00%> (ø)
src/serializers/type_serializers/dataclass.rs	91.89% <100.00%> (ø)
src/validators/arguments.rs	99.57% <100.00%> (ø)
src/validators/dataclass.rs	97.72% <100.00%> (ø)
src/validators/model.rs	97.83% <100.00%> (ø)
src/validators/model_fields.rs	98.25% <100.00%> (ø)
src/validators/typed_dict.rs	96.93% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[codspeed-hq]

CodSpeed Performance Report

Merging #1088 will not alter performance

_{Comparing dh/remove-spurious-interns (5dc764e) with main (3d3f406)}

Summary

✅ 140 untouched benchmarks

[davidhewitt]

please review