Bump undici and @xmtp/react-sdk in /other/xmtp-example

Removes [undici](https://github.com/nodejs/undici). It's no longer used after updating ancestor dependency [@xmtp/react-sdk](https://github.com/xmtp/xmtp-web/tree/HEAD/packages/react-sdk). These dependencies need to be updated together.


Removes `undici`

Updates `@xmtp/react-sdk` from 6.0.1 to 9.0.0
- [Release notes](https://github.com/xmtp/xmtp-web/releases)
- [Changelog](https://github.com/xmtp/xmtp-web/blob/main/packages/react-sdk/CHANGELOG.md)
- [Commits](https://github.com/xmtp/xmtp-web/commits/@xmtp/[email protected]/packages/react-sdk)

---
updated-dependencies:
- dependency-name: undici
  dependency-version: 
  dependency-type: indirect
- dependency-name: "@xmtp/react-sdk"
  dependency-version: 9.0.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

other/xmtp-example/package-lock.json

@@ -13,7 +13,7 @@
   "//IMP START": "IMP START - Web3Auth Installation",
   "dependencies": {
     "@web3auth/modal": "^10.3.0",
-    "@xmtp/react-sdk": "^6.0.0",
+    "@xmtp/react-sdk": "^9.0.0",
     "ethers": "^6.13.2",
     "react": "^18.3.1",
     "react-dom": "^18.3.1"