chore(deps): bump gatsby-plugin-mdx from 1.0.70 to 1.0.73

Bumps [gatsby-plugin-mdx](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-mdx) from 1.0.70 to 1.0.73.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-mdx/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-plugin-mdx)

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

Author: dependabot-preview[bot]

yarn.lock

@@ -10846,9 +10846,9 @@ gatsby-plugin-google-fonts@^1.0.0:
   integrity sha512-p1NVkn27GUnDA5qHM+Z4cCcLCJIardzZXMon3640sT4xuL/AZJbsx3HEt2KY/5oZu0UXIkytkxzV2Da4rQeUIg==
 
 gatsby-plugin-mdx@^1.0.4, gatsby-plugin-mdx@^1.0.70:
-  version "1.0.70"
-  resolved "https://registry.yarnpkg.com/gatsby-plugin-mdx/-/gatsby-plugin-mdx-1.0.70.tgz#97613bf6888a74b425d1a8e8b6cb21250c50bc07"
-  integrity sha512-nHZHcZgrO17KpcwjKJs1E9DaAyg0Qy4hCugTIuOAGKNZfYKNfwf5n5LZoxK5/VUXpFqM/Zfm3ubKVmXFGw5ZPw==
+  version "1.0.73"
+  resolved "https://registry.yarnpkg.com/gatsby-plugin-mdx/-/gatsby-plugin-mdx-1.0.73.tgz#cd9187e362ffae559c111ca6ce931c35276d8aa5"
+  integrity sha512-QEYlDV9o25NNbP0C86G3z+E2yrzb3kWEMqD51u85sRUdIMpMeYto2ZkPzTBDinmkUa4/vQYuoL9th69bukNtEg==
   dependencies:
     "@babel/core" "^7.7.5"
     "@babel/generator" "^7.7.4"