build(deps-dev): bump @astrojs/mdx from 4.3.7 to 4.3.12

Bumps [@astrojs/mdx](https://github.com/withastro/astro/tree/HEAD/packages/integrations/mdx) from 4.3.7 to 4.3.12.
- [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)

---
updated-dependencies:
- dependency-name: "@astrojs/mdx"
  dependency-version: 4.3.12
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

apps/starlight/package.json

@@ -12,7 +12,7 @@
   },
   "devDependencies": {
     "@astrojs/check": "0.9.4",
-    "@astrojs/mdx": "4.3.7",
+    "@astrojs/mdx": "4.3.12",
     "@astrojs/solid-js": "5.1.3",
     "@astrojs/starlight": "0.36.2",
     "@spuxx/browser-utils": "workspace:@spuxx/browser-utils@*",