build(deps): bump @docusaurus/core in /website

Bumps [@docusaurus/core](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus) from 2.0.0-beta.2 to 2.0.0-beta.4.
- [Release notes](https://github.com/facebook/docusaurus/releases)
- [Changelog](https://github.com/facebook/docusaurus/blob/master/CHANGELOG.md)
- [Commits](https://github.com/facebook/docusaurus/commits/v2.0.0-beta.4/packages/docusaurus)

---
updated-dependencies:
- dependency-name: "@docusaurus/core"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

website/package.json

@@ -16,7 +16,7 @@
     "write-heading-ids": "docusaurus write-heading-ids"
   },
   "dependencies": {
-    "@docusaurus/core": "2.0.0-beta.2",
+    "@docusaurus/core": "2.0.0-beta.4",
     "@docusaurus/preset-classic": "2.0.0-beta.2",
     "@mdx-js/react": "^1.6.21",
     "@svgr/webpack": "^5.5.0",