Update dependency next to v16

Author: renovate[bot]

package-lock.json

@@ -20,7 +20,7 @@
     "clsx": "^2.0.0",
     "date-fns": "^4.0.0",
     "framer-motion": "^12.0.0",
-    "next": "^15.0.0",
+    "next": "^16.0.0",
     "next-sitemap": "^4.2.3",
     "nextra": "^3.0.0",
     "nextra-theme-docs": "^3.0.0",