Ruby 4.0 compatibility, contributor handling, and citation output fixes

[kaysiz]

Purpose

This PR addresses Ruby 4.0 compatibility issues with citeproc/csl-ruby, ensures correct handling of DataCite contributors, and improves citation output logic:

• Monkey-patches CiteProc::Variable to recognize contributor and accepted-date as valid fields, updating @fields, @types, and @factories.
  • CiteProc::Variable field/type/factory logic
  • CiteProc::Variable @factories mapping
• Filters contributors so that only those not already listed as creators, editors, or translators are passed to CiteProc, preventing duplication in citations.
• Ensures correct citation output for both software and book types, matching CSL style expectations.
• Adds/updates specs to verify contributor handling for both software and book types.

closes: Add github issue that originated this PR

Approach

• Fixes "undefined method 'take'" and "undefined method 'personal?'" errors under Ruby 4.0.
• Ensures contributors like TCCON (ResearchGroup) are only shown in citations when the CSL style and type (e.g., book) support it.
• For software type, contributors are present in the data but not rendered in APA and most CSL styles (by design).
• For book type, contributors appear as expected (e.g., "(with TCCON)").
• Test coverage.

References

• CiteProc::Variable field/type/factory logic
• CiteProc::Variable @factories mapping
• CSL style field documentation

Open Questions and Pre-Merge TODOs

Learning

Types of changes

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

• Breaking change (fix or feature that would cause existing functionality to change)

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