Bump truffle from 5.1.48 to 5.6.2 in /ui

Bumps [truffle](https://github.com/trufflesuite/truffle/tree/HEAD/packages/truffle) from 5.1.48 to 5.6.2.
- [Release notes](https://github.com/trufflesuite/truffle/releases)
- [Commits](https://github.com/trufflesuite/truffle/commits/[email protected]/packages/truffle)

---
updated-dependencies:
- dependency-name: truffle
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

ui/package.json

@@ -13,7 +13,7 @@
     "@openzeppelin/test-helpers": "^0.5.10",
     "concurrently": "^5.3.0",
     "ganache-cli": "^6.12.0",
-    "truffle": "^5.1.48",
+    "truffle": "^5.6.2",
     "wait-on": "^5.2.1"
   },
   "workspaces": {