Bump @mdx-js/mdx from 2.3.0 to 3.0.0

Bumps [@mdx-js/mdx](https://github.com/mdx-js/mdx/tree/HEAD/packages/mdx) from 2.3.0 to 3.0.0.
- [Release notes](https://github.com/mdx-js/mdx/releases)
- [Changelog](https://github.com/mdx-js/mdx/blob/main/changelog.md)
- [Commits](https://github.com/mdx-js/mdx/commits/3.0.0/packages/mdx)

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

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

Author: dependabot[bot]

gatsby-theme-doctocat-typescript/package.json

@@ -24,7 +24,7 @@
   "license": "MIT",
   "dependencies": {
     "@gatsbyjs/reach-router": "^2.0.1",
-    "@mdx-js/mdx": "^2.3.0",
+    "@mdx-js/mdx": "^3.0.0",
     "@mdx-js/react": "^2.3.0",
     "@octokit/types": "^12.3.0",
     "@primer/component-metadata": "^0.5.1",