Bump ethers from 6.15.0 to 6.16.0 in /frontend

Bumps [ethers](https://github.com/ethers-io/ethers.js) from 6.15.0 to 6.16.0.
- [Release notes](https://github.com/ethers-io/ethers.js/releases)
- [Changelog](https://github.com/ethers-io/ethers.js/blob/main/CHANGELOG.md)
- [Commits](https://github.com/ethers-io/ethers.js/compare/v6.15.0...v6.16.0)

---
updated-dependencies:
- dependency-name: ethers
  dependency-version: 6.16.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

frontend/package.json

@@ -48,7 +48,7 @@
     "crypto-js": "^4.2.0",
     "date-fns": "^4.1.0",
     "embla-carousel-react": "^8.5.1",
-    "ethers": "^6.15.0",
+    "ethers": "^6.16.0",
     "firebase": "^12.12.1",
     "geist": "^1.4.0",
     "input-otp": "^1.4.1",