build(deps): bump @astrojs/mdx from 3.1.0 to 3.1.1

Bumps [@astrojs/mdx](https://github.com/withastro/astro/tree/HEAD/packages/integrations/mdx) from 3.1.0 to 3.1.1.
- [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/mdx@3.1.1/packages/integrations/mdx)

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

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -19,7 +19,7 @@
     "start": "astro dev"
   },
   "dependencies": {
-    "@astrojs/mdx": "^3.1.0",
+    "@astrojs/mdx": "^3.1.1",
     "@astrojs/react": "^3.5.0",
     "@astrojs/rss": "^4.0.6",
     "@astrojs/sitemap": "^3.1.5",