chore(deps-dev): bump @docusaurus/tsconfig in /testsite

Bumps [@docusaurus/tsconfig](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus-tsconfig) from 3.0.0-alpha.0 to 3.0.0-beta.0.
- [Release notes](https://github.com/facebook/docusaurus/releases)
- [Changelog](https://github.com/facebook/docusaurus/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/docusaurus/commits/v3.0.0-beta.0/packages/docusaurus-tsconfig)

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

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

testsite/package.json

@@ -30,7 +30,7 @@
   },
   "devDependencies": {
     "@docusaurus/module-type-aliases": "3.0.0-alpha.0",
-    "@docusaurus/tsconfig": "3.0.0-alpha.0",
+    "@docusaurus/tsconfig": "3.0.0-beta.0",
     "@types/react": "^18.2.21",
     "@types/react-dom": "^18.2.7",
     "typescript": "^5.2.2"