Bump @astrojs/mdx from 4.3.7 to 4.3.8

Bumps [@astrojs/mdx](https://github.com/withastro/astro/tree/HEAD/packages/integrations/mdx) from 4.3.7 to 4.3.8.
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/main/packages/integrations/mdx/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/HEAD/packages/integrations/mdx)

---
updated-dependencies:
- dependency-name: "@astrojs/mdx"
  dependency-version: 4.3.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]