build(deps-dev): bump @openzeppelin/contracts in /contracts

Bumps [@openzeppelin/contracts](https://github.com/OpenZeppelin/openzeppelin-contracts) from 4.9.3 to 4.9.6.
- [Release notes](https://github.com/OpenZeppelin/openzeppelin-contracts/releases)
- [Changelog](https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/CHANGELOG.md)
- [Commits](OpenZeppelin/openzeppelin-contracts@v4.9.3...v4.9.6)

---
updated-dependencies:
- dependency-name: "@openzeppelin/contracts"
  dependency-type: direct:development
...

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

contracts/package.json

@@ -17,7 +17,7 @@
   "license": "MIT",
   "devDependencies": {
     "@nomicfoundation/hardhat-toolbox": "^3.0.0",
-    "@openzeppelin/contracts": "^4.9.3",
+    "@openzeppelin/contracts": "^4.9.6",
     "@openzeppelin/contracts-upgradeable": "^4.9.3",
     "@openzeppelin/hardhat-upgrades": "^2.2.1",
     "hardhat": "^2.17.1",