chore(deps-dev): bump the astro group across 1 directory with 2 updates (#5777)

Bumps the astro group with 2 updates in the / directory: [@astrojs/mdx](https://github.com/withastro/astro/tree/HEAD/packages/integrations/mdx) and [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro).


Updates `@astrojs/mdx` from 3.1.8 to 3.1.9
- [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/@astrojs/[email protected]/packages/integrations/mdx)

Updates `astro` from 4.16.7 to 4.16.16
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/main/packages/astro/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/[email protected]/packages/astro)

---
updated-dependencies:
- dependency-name: "@astrojs/mdx"
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: astro
- dependency-name: astro
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: astro
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]