Bump gatsby-plugin-mdx from 1.10.0 to 2.14.1

Bumps [gatsby-plugin-mdx](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-mdx) from 1.10.0 to 2.14.1.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/gatsby-plugin-mdx@2.14.1/packages/gatsby-plugin-mdx/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-mdx@2.14.1/packages/gatsby-plugin-mdx)

---
updated-dependencies:
- dependency-name: gatsby-plugin-mdx
  dependency-type: direct:production
...

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

Author: dependabot[bot]

package.json

@@ -41,7 +41,7 @@
     "gatsby": "^2.10.4",
     "gatsby-cli": "^2.7.3",
     "gatsby-image": "^2.2.3",
-    "gatsby-plugin-mdx": "^1.0.16",
+    "gatsby-plugin-mdx": "^2.14.1",
     "gatsby-plugin-react-helmet": "^3.1.0",
     "gatsby-plugin-sharp": "^2.2.1",
     "gatsby-plugin-styled-components": "^3.1.1",