fix: restore @prismicio/client/richtext type exports

[angeloashmore]

Resolves: #427

Description

This PR restores @prismicio/client/richtext type exports.

The types file was changed to dist/richtext.d.ts from dist/richtext/index.d.ts after the change to tsdown. package.json was accidentally not updated to reflect this change.

Checklist

• A comprehensive Linear ticket, providing sufficient context and details to facilitate the review of the PR, is linked to the PR.
• If my changes require tests, I added them.
• If my changes affect backward compatibility, it has been discussed.
• If my changes require an update to the CONTRIBUTING.md guide, I updated it.

Preview

How to QA ¹

Footnotes

1. Please use these labels when submitting a review:
   ❓ #ask: Ask a question.
   💡 #idea: Suggest an idea.
   ⚠️ #issue: Strongly suggest a change.
   🎉 #nice: Share a compliment. ↩