Bump @nomiclabs/hardhat-etherscan from 2.1.8 to 3.0.3

Bumps [@nomiclabs/hardhat-etherscan](https://github.com/nomiclabs/hardhat) from 2.1.8 to 3.0.3.
- [Release notes](https://github.com/nomiclabs/hardhat/releases)
- [Commits](https://github.com/nomiclabs/hardhat/compare/@nomiclabs/hardhat-etherscan@2.1.8...@nomiclabs/hardhat-etherscan@3.0.3)

---
updated-dependencies:
- dependency-name: "@nomiclabs/hardhat-etherscan"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

package.json

@@ -40,7 +40,7 @@
   },
   "devDependencies": {
     "@nomiclabs/hardhat-ethers": "^2.0.4",
-    "@nomiclabs/hardhat-etherscan": "^2.1.8",
+    "@nomiclabs/hardhat-etherscan": "^3.0.3",
     "@nomiclabs/hardhat-solhint": "^2.0.0",
     "@nomiclabs/hardhat-waffle": "^2.0.2",
     "@shardlabs/starknet-hardhat-plugin": "^0.5.3",