ignore @mdx-js/loader (#6958)

Author: chenxsan

.github/dependabot.yml

@@ -11,6 +11,7 @@ updates:
       - dependency-name: "react"
       - dependency-name: "react-dom"
       - dependency-name: "@docsearch/react" # unfortunately I don't have the app id
+      - dependency-name: "@mdx-js/loader" # we can't update this due to incompatibility with our code base
       - dependency-name: "remark-gfm" # breaking change
     groups:
       dependencies: