fix(deps): update dependency astro to v6

Author: renovate[bot]

package.json

@@ -15,7 +15,7 @@
     "@astrojs/mdx": "^4.3.6",
     "@astrojs/rss": "^4.0.12",
     "@astrojs/sitemap": "^3.6.0",
-    "astro": "^5.14.1",
+    "astro": "^6.0.0",
     "typescript": "^5.3.3"
   }
 }