Bump react from 18.3.1 to 19.2.0 in /site

Bumps [react](https://github.com/facebook/react/tree/HEAD/packages/react) from 18.3.1 to 19.2.0.
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/v19.2.0/packages/react)

---
updated-dependencies:
- dependency-name: react
  dependency-version: 19.2.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

site/package-lock.json

@@ -25,7 +25,7 @@
     "gatsby-source-filesystem": "^5.14.0",
     "gatsby-transformer-sharp": "^5.14.0",
     "prismjs": "^1.30.0",
-    "react": "^18.3.1",
+    "react": "^19.2.0",
     "react-dom": "^18.3.1",
     "style-to-object": "^1.0.11"
   },