fix(deps): update dependency astro to v5.15.9 [security] (#133)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

package-lock.json

@@ -10,7 +10,7 @@
     "cms": "bunx decap-server"
   },
   "dependencies": {
-    "astro": "5.15.8",
+    "astro": "5.15.9",
     "bootstrap-italia": "2.17.0",
     "decap-cms-app": "3.9.0",
     "marked": "16.4.2",