Update nextjs monorepo to v15

Author: renovate[bot]

web/package.json

@@ -17,7 +17,7 @@
     "@livekit/components-styles": "^1.1.2",
     "livekit-client": "^2.6.0",
     "livekit-server-sdk": "^2.6.1",
-    "next": "14.2.10",
+    "next": "15.1.1",
     "react": "^18",
     "react-dom": "^18",
     "react-draggable": "^4.4.6"
@@ -27,7 +27,7 @@
     "@types/react": "^18",
     "@types/react-dom": "^18",
     "eslint": "^8",
-    "eslint-config-next": "14.2.18",
+    "eslint-config-next": "15.1.1",
     "eslint-config-prettier": "^8.10.0",
     "eslint-plugin-prettier": "^5.1.3",
     "eslint-plugin-unused-imports": "^3.0.0",