feat: upgrade ethers from 5.7.2 to 6.0.8

Snyk has created this PR to upgrade ethers from 5.7.2 to 6.0.8.

See this package in npm:
https://www.npmjs.com/package/ethers

See this project in Snyk:
https://app.snyk.io/org/jwood3794/project/6ea6390d-6eff-4251-a352-a0e70e8e65ea?utm_source=github&utm_medium=referral&page=upgrade-pr

assets/eip-4400/package.json

@@ -9,7 +9,7 @@
     "@types/node": "^14.14.6",
     "chai": "^4.3.4",
     "ethereum-waffle": "^3.4.0",
-    "ethers": "^5.4.7",
+    "ethers": "^6.0.8",
     "hardhat": "^2.6.7",
     "hardhat-abi-exporter": "^2.3.1",
     "hardhat-typechain": "^0.3.3",