chore(deps): update mdx monorepo to v1.6.22

Author: renovate-bot

package.json

@@ -9,8 +9,8 @@
     "dev": "gatsby develop"
   },
   "dependencies": {
-    "@mdx-js/mdx": "1.6.18",
-    "@mdx-js/react": "1.6.18",
+    "@mdx-js/mdx": "1.6.22",
+    "@mdx-js/react": "1.6.22",
     "classnames": "2.2.6",
     "gatsby": "2.24.68",
     "gatsby-image": "2.4.21",