fix(deps): update dependency astro to v5.18.1

Author: renovate[bot]

starlight/package.json

@@ -12,7 +12,7 @@
     "@astrojs/starlight": "0.37.5",
     "@iconify-json/ri": "^1.2.7",
     "@tailwindcss/vite": "^4.1.18",
-    "astro": "5.17.1",
+    "astro": "5.18.1",
     "astro-icon": "^1.1.5",
     "reading-time": "^1.5.0",
     "sharp": "^0.34.2",