Update dependency gatsby-plugin-mdx to v2 [SECURITY]

Author: renovate[bot]

package.json

@@ -18,7 +18,7 @@
     "gatsby-image": "2.4.17",
     "gatsby-plugin-catch-links": "2.3.11",
     "gatsby-plugin-layout": "1.3.10",
-    "gatsby-plugin-mdx": "1.2.38",
+    "gatsby-plugin-mdx": "2.14.1",
     "gatsby-remark-images": "3.3.29",
     "gatsby-remark-smartypants": "2.3.10",
     "gatsby-source-filesystem": "2.3.28",