Upgrade MDX (#95)

Align version numbers with the latest included in `gatsby-plugin-mdx`,
to match https://github.com/Lullabot/architecture.

This is a stab at resolving Lullabot/architecture#494

packages/gatsby-theme-adr/package.json

@@ -23,8 +23,8 @@
     "@formatjs/cli": "^5.1.7",
     "@headlessui/react": "^1.7.5",
     "@heroicons/react": "^1.0.6",
-    "@mdx-js/mdx": "^2.1.5",
-    "@mdx-js/react": "^2.1.5",
+    "@mdx-js/mdx": "^2.3.0",
+    "@mdx-js/react": "^2.3.0",
     "@tailwindcss/forms": "^0.5.3",
     "@tailwindcss/typography": "^0.5.8",
     "autoprefixer": "^10.4.13",

yarn.lock

@@ -1727,10 +1727,33 @@
     unist-util-visit "^4.0.0"
     vfile "^5.0.0"
 
-"@mdx-js/react@^2.1.5":
-  version "2.1.5"
-  resolved "https://registry.yarnpkg.com/@mdx-js/react/-/react-2.1.5.tgz#8225a867dae6f845ae5b0ec15bb454c23be3f576"
-  integrity sha512-3Az1I6SAWA9R38rYjz5rXBrGKeZhq96CSSyQtqY+maPj8stBsoUH5pNcmIixuGkufYsh8F5+ka2CVPo2fycWZw==
+"@mdx-js/mdx@^2.3.0":
+  version "2.3.0"
+  resolved "https://registry.yarnpkg.com/@mdx-js/mdx/-/mdx-2.3.0.tgz#d65d8c3c28f3f46bb0e7cb3bf7613b39980671a9"
+  integrity sha512-jLuwRlz8DQfQNiUCJR50Y09CGPq3fLtmtUQfVrj79E0JWu3dvsVcxVIcfhR5h0iXu+/z++zDrYeiJqifRynJkA==
+  dependencies:
+    "@types/estree-jsx" "^1.0.0"
+    "@types/mdx" "^2.0.0"
+    estree-util-build-jsx "^2.0.0"
+    estree-util-is-identifier-name "^2.0.0"
+    estree-util-to-js "^1.1.0"
+    estree-walker "^3.0.0"
+    hast-util-to-estree "^2.0.0"
+    markdown-extensions "^1.0.0"
+    periscopic "^3.0.0"
+    remark-mdx "^2.0.0"
+    remark-parse "^10.0.0"
+    remark-rehype "^10.0.0"
+    unified "^10.0.0"
+    unist-util-position-from-estree "^1.0.0"
+    unist-util-stringify-position "^3.0.0"
+    unist-util-visit "^4.0.0"
+    vfile "^5.0.0"
+
+"@mdx-js/react@^2.3.0":
+  version "2.3.0"
+  resolved "https://registry.yarnpkg.com/@mdx-js/react/-/react-2.3.0.tgz#4208bd6d70f0d0831def28ef28c26149b03180b3"
+  integrity sha512-zQH//gdOmuu7nt2oJR29vFhDv88oGPmVw6BggmrHeMI+xgEkp1B2dX9/bMBSYtK0dyLX/aOmesKS09g222K1/g==
   dependencies:
     "@types/mdx" "^2.0.0"
     "@types/react" ">=16"