pin old @mdx-js/react to fix docusaurus

see
facebook/docusaurus#6520 (comment)
for details

packages/website/package.json

@@ -15,6 +15,7 @@
     "@docusaurus/core": "2.3.1",
     "@docusaurus/preset-classic": "2.3.1",
     "@heroicons/react": "^1.0.6",
+    "@mdx-js/react": "1.6.22",
     "@quri/squiggle-components": "^0.6.0",
     "base64-js": "^1.5.1",
     "clsx": "^1.2.1",

yarn.lock

@@ -3409,7 +3409,7 @@
     unist-builder "2.0.3"
     unist-util-visit "2.0.3"
 
-"@mdx-js/react@^1.6.22":
+"@mdx-js/react@1.6.22", "@mdx-js/react@^1.6.22":
   version "1.6.22"
   resolved "https://registry.yarnpkg.com/@mdx-js/react/-/react-1.6.22.tgz#ae09b4744fddc74714ee9f9d6f17a66e77c43573"
   integrity sha512-TDoPum4SHdfPiGSAaRBw7ECyI8VaHpK8GJugbJIJuqyh6kzw9ZLJZW3HGL3NNrJGxcAixUvqROm+YuQOo5eXtg==
@@ -5321,7 +5321,7 @@
     "@types/history" "^4.7.11"
     "@types/react" "*"
 
-"@types/react@*", "@types/react@>=16", "@types/react@^18.0.1", "@types/react@^18.0.21", "@types/react@^18.0.28":
+"@types/react@*", "@types/react@>=16", "@types/react@^18.0.21", "@types/react@^18.0.28":
   version "18.0.33"
   resolved "https://registry.yarnpkg.com/@types/react/-/react-18.0.33.tgz#a1575160cb4376787c2f5fe0312302f824baa61e"
   integrity sha512-sHxzVxeanvQyQ1lr8NSHaj0kDzcNiGpILEVt69g9S31/7PfMvNCKLKcsHw4lYKjs3cGNJjXSP4mYzX43QlnjNA==
@@ -15265,7 +15265,7 @@ react-use@^17.4.0:
     ts-easing "^0.2.0"
     tslib "^2.1.0"
 
-react@^18.0.0, react@^18.1.0, react@^18.2.0:
+react@^18.1.0, react@^18.2.0:
   version "18.2.0"
   resolved "https://registry.yarnpkg.com/react/-/react-18.2.0.tgz#555bd98592883255fa00de14f1151a917b5d77d5"
   integrity sha512-/3IjMdb2L9QbBdWiW5e3P2/npwMBaU9mHCSCUzNln0ZCYbcfTsGbTJrU/kGemdH2IWmB2ioZ+zkxtmq6g09fGQ==