Update dependency ethereumjs-util to v7.1.5

Author: renovate[bot]

package.json

@@ -38,7 +38,7 @@
     "@openzeppelin/upgrades": "2.8.0",
     "bignumber.js": "9.0.1",
     "ethereum-waffle": "2.5.1",
-    "ethereumjs-util": "7.0.6",
+    "ethereumjs-util": "7.1.5",
     "hardlydifficult-eth": "1.1.3",
     "hardlydifficult-ethereum-contracts": "0.11.1",
     "papaparse": "5.3.0",