Update mdx monorepo to v1.6.6

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
@mdx-js/mdx (source)	dependencies	patch	1.6.5 -> 1.6.6
@mdx-js/react (source)	dependencies	patch	1.6.5 -> 1.6.6

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Release Notes

mdx-js/mdx

### [`v1.6.6`](https://togithub.com/mdx-js/mdx/compare/v1.6.5...v1.6.6) [Compare Source](https://togithub.com/mdx-js/mdx/compare/v1.6.5...v1.6.6)

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