fix: replace deprecated `IntegrationFields` type with `IntegrationField` type

[angeloashmore]

Types of changes

• [ ] Chore (a non-breaking change which is related to package maintenance)
• [x] Bug fix (a non-breaking change which fixes an issue)
• [ ] New feature (a non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Description

This PR fixes prismic-ts-codegen by using the correct non-deprecated IntegrationField type.

IntegrationFields (with an "s") was deprecated in @prismicio/client v7. Although IntegrationFields is still a valid API, TypeScript will warn about its deprecation status, and the type will eventually be removed from @prismicio/cilent.

Checklist:

• [ ] My change requires an update to the official documentation.
• [x] All TSDoc comments are up-to-date and new ones have been added where necessary.
• [x] All new and existing tests are passing.

🐰

[codecov-commenter]

Codecov Report

Merging #48 (a02ca39) into main (68c6fb9) will not change coverage. The diff coverage is 100.00%.

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@@           Coverage Diff           @@
##             main      #48   +/-   ##
=======================================
  Coverage   98.73%   98.73%           
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  Files          23       23           
  Lines        1655     1655           
  Branches      142      142           
=======================================
  Hits         1634     1634           
  Misses         21       21           

Impacted Files	Coverage Δ
src/lib/addInterfacePropertiesForFields.ts	98.64% <100.00%> (ø)