feat(docs): update supported TypeScript version

[siketyan]

Summary

Updated the supported TypeScript version in the language support page as Biome is working well with the latest TypeScript.

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Tracked Files

Locale	File	Note
en	src/content/docs/internals/language-support.mdx	Source changed, localizations will be marked as outdated.

Warnings reference

Icon	Description
🔄️	The source for this localization has been updated since the creation of this pull request, make sure all changes in the source have been applied.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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Walkthrough

Updates the documented TypeScript support version from 5.6 to 5.9 in the language-support documentation. This is a straightforward documentation-only change with a single line modification and no functional code alterations.

Possibly related PRs

• chore: update language support #3957: Modifies the same language-support documentation file for related version information updates

Suggested labels

A-Documentation

Suggested reviewers

• ematipico

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: updating the supported TypeScript version from 5.6 to 5.9 in the documentation.
Description check	✅ Passed	The description is directly related to the changeset, explaining the motivation for updating the TypeScript version documentation.

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/update-typescript-version

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