Bump astro from 5.14.5 to 5.15.9 in /docs

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 5.14.5 to 5.15.9.
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/main/packages/astro/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/[email protected]/packages/astro)

---
updated-dependencies:
- dependency-name: astro
  dependency-version: 5.15.9
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/package.json

@@ -16,7 +16,7 @@
     "@phosphor-icons/react": "^2.1.10",
     "@types/react": "^19.2.2",
     "@types/react-dom": "^19.2.2",
-    "astro": "^5.14.5",
+    "astro": "^5.15.9",
     "react": "^19.2.0",
     "react-dom": "^19.2.0",
     "remark-gemoji": "^8.0.0",