Bump @next/mdx from 9.2.0 to 9.2.1

Bumps [@next/mdx](https://github.com/zeit/next.js/tree/HEAD/packages/next-mdx) from 9.2.0 to 9.2.1.
- [Release notes](https://github.com/zeit/next.js/releases)
- [Commits](https://github.com/zeit/next.js/commits/v9.2.1/packages/next-mdx)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

yarn.lock

@@ -2819,9 +2819,9 @@
     glob-to-regexp "^0.3.0"
 
 "@next/mdx@^9.0.3":
-  version "9.2.0"
-  resolved "https://registry.yarnpkg.com/@next/mdx/-/mdx-9.2.0.tgz#f705fd11357f84bec14c4432f6f176ba33fa6345"
-  integrity sha512-UvmpvBr15g4nxQcppiOT3Ej8CLJ9wx/aUICuF4HDCdip5aN9R9epsuZy38y08kvbnbeOlpuJPDpu46A4joXvzA==
+  version "9.2.1"
+  resolved "https://registry.yarnpkg.com/@next/mdx/-/mdx-9.2.1.tgz#0cc3016a03572e34e5fcb7bb3137fc74266c3f97"
+  integrity sha512-Nhwxlg/CMExjTdXVDc7mbx4UkSGr/ye36iFe8fAj71MyWAjX3y+GB+VG7iLU564y3TqeuLG4iWxwZpmmh/HJxQ==
 
 "@nodelib/[email protected]":
   version "2.1.3"