fix(deps): update dependency next to v15 [security]

Author: renovate[bot]

app/package.json

@@ -16,7 +16,7 @@
     "autoprefixer": "10.4.12",
     "graphql": "16.6.0",
     "javascript-time-ago": "2.5.7",
-    "next": "12.3.1",
+    "next": "15.5.14",
     "postcss": "8.4.17",
     "react": "17.0.2",
     "react-dom": "17.0.2",