build(deps): bump next from 14.2.26 to 15.2.4 in /explorer-nextjs

Bumps [next](https://github.com/vercel/next.js) from 14.2.26 to 15.2.4.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v14.2.26...v15.2.4)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.2.4
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

explorer-nextjs/package.json

@@ -11,7 +11,7 @@
   "dependencies": {
     "@nymproject/react": "^1.0.0",
     "@nymproject/nym-validator-client": "0.18.0",
-    "next": "14.2.26",
+    "next": "15.2.4",
     "react": "^18",
     "react-dom": "^18",
     "react-error-boundary": "^4.0.13",