Bump @babel/core in /src/Elastic.Documentation.Site (#1926)

Bumps [@babel/core](https://github.com/babel/babel/tree/HEAD/packages/babel-core) from 7.28.3 to 7.28.4.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/main/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/commits/v7.28.4/packages/babel-core)

---
updated-dependencies:
- dependency-name: "@babel/core"
  dependency-version: 7.28.4
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

src/Elastic.Documentation.Site/package-lock.json

@@ -34,7 +34,7 @@
   },
   "private": true,
   "devDependencies": {
-    "@babel/core": "7.28.3",
+    "@babel/core": "7.28.4",
     "@babel/preset-env": "7.28.3",
     "@babel/preset-react": "7.27.1",
     "@babel/preset-typescript": "7.27.1",