chore(deps): bump astro from 5.15.3 to 5.15.9

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 5.15.3 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]

package.json

@@ -11,7 +11,7 @@
   },
   "dependencies": {
     "@astrojs/starlight": "^0.36.0",
-    "astro": "^5.14.3",
+    "astro": "^5.15.9",
     "sharp": "^0.34.3"
   },
   "packageManager": "[email protected]",