build(deps): Bump @mysten/sui from 2.20.3 to 2.22.0 in /backend

Bumps [@mysten/sui](https://github.com/MystenLabs/ts-sdks) from 2.20.3 to 2.22.0.
- [Release notes](https://github.com/MystenLabs/ts-sdks/releases)
- [Commits](https://github.com/MystenLabs/ts-sdks/commits)

---
updated-dependencies:
- dependency-name: "@mysten/sui"
  dependency-version: 2.22.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

backend/package-lock.json

@@ -26,7 +26,7 @@
   "license": "AGPL-3.0-only-or-later",
   "dependencies": {
     "@mysten/payment-kit": "^0.2.3",
-    "@mysten/sui": "^2.19.0",
+    "@mysten/sui": "^2.22.0",
     "@mysten/walrus": "^1.2.1",
     "cors": "^2.8.6",
     "dotenv": "^17.4.2",