Update dependency next to v15 [SECURITY]

Author: renovate[bot]

package.json

@@ -13,7 +13,7 @@
     "dotenv": "^8.0.0",
     "express": "^4.16.4",
     "minimist": "^1.2.0",
-    "next": "^8.0.0",
+    "next": "^15.0.0",
     "next-routes-middleware": "^3.3.0",
     "react": "^16.6.3",
     "react-dom": "^16.6.3"