chore(deps): update dependency gatsby-plugin-mdx to v2 [security]

Author: renovate[bot]

package.json

@@ -14,7 +14,7 @@
     "classnames": "2.2.6",
     "gatsby": "2.24.68",
     "gatsby-image": "2.4.21",
-    "gatsby-plugin-mdx": "1.2.44",
+    "gatsby-plugin-mdx": "2.14.1",
     "gatsby-plugin-postcss": "2.3.13",
     "gatsby-plugin-react-helmet": "3.3.13",
     "gatsby-plugin-react-svg": "3.0.0",