dependabot: bump @zetachain/toolkit from 10.0.0 to 12.0.0 in /contracts

Bumps @zetachain/toolkit from 10.0.0 to 12.0.0.

---
updated-dependencies:
- dependency-name: "@zetachain/toolkit"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

contracts/package.json

@@ -27,7 +27,7 @@
     "@types/node": ">=12.0.0",
     "@typescript-eslint/eslint-plugin": "^5.59.9",
     "@typescript-eslint/parser": "^5.59.9",
-    "@zetachain/toolkit": "^10.0.0",
+    "@zetachain/toolkit": "^12.0.0",
     "axios": "^1.3.6",
     "chai": "^4.2.0",
     "dotenv": "^16.0.3",