fix(deps): update dependency next to v15

Author: renovate[bot]

package.json

@@ -23,7 +23,7 @@
     "@typescript-eslint/parser": "^8.18.0",
     "eslint-config-next": "^15.1.0",
     "eslint-config-prettier": "^10.0.0",
-    "next": "^14.2.4",
+    "next": "^15.0.0",
     "nextra": "^3.0.0",
     "nextra-theme-docs": "^3.0.0",
     "react": "^19.0.0",