Bump astro from 5.12.2 to 5.15.9 (#12)

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 5.12.2 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/astro@5.15.9/packages/astro)

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

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Author: dependabot[bot]

package.json

@@ -15,7 +15,7 @@
     "@astrojs/check": "^0.9.4",
     "@astrojs/sitemap": "^3.4.1",
     "@astrojs/tailwind": "^6.0.2",
-    "astro": "^5.12.2",
+    "astro": "^5.15.9",
     "astro-seo-meta": "^4.2.0",
     "astro-seo-schema": "^5.0.0",
     "tailwindcss": "^3.4.17",