Ensure ethereumjs-util matches Bancor

package-lock.json

@@ -5791,13 +5791,13 @@
       }
     },
     "ethereumjs-util": {
-      "version": "6.1.0",
-      "resolved": "https://registry.npmjs.org/ethereumjs-util/-/ethereumjs-util-6.1.0.tgz",
-      "integrity": "sha512-URESKMFbDeJxnAxPppnk2fN6Y3BIatn9fwn76Lm8bQlt+s52TpG8dN9M66MLPuRAiAOIqL3dfwqWJf0sd0fL0Q==",
+      "version": "5.2.0",
+      "resolved": "https://registry.npmjs.org/ethereumjs-util/-/ethereumjs-util-5.2.0.tgz",
+      "integrity": "sha512-CJAKdI0wgMbQFLlLRtZKGcy/L6pzVRgelIZqRqNbuVFM3K9VEnyfbcvz0ncWMRNCe4kaHWjwRYQcYMucmwsnWA==",
       "requires": {
         "bn.js": "^4.11.0",
         "create-hash": "^1.1.2",
-        "ethjs-util": "0.1.6",
+        "ethjs-util": "^0.1.3",
         "keccak": "^1.0.2",
         "rlp": "^2.0.0",
         "safe-buffer": "^5.1.1",

package.json

@@ -7,7 +7,7 @@
     "connected-react-router": "^6.3.2",
     "debounce": "^1.2.0",
     "decimal.js": "^10.0.2",
-    "ethereumjs-util": "^6.0.0",
+    "ethereumjs-util": "^5.2.0",
     "history": "^4.7.2",
     "moment": "^2.24.0",
     "node-sass": "^4.11.0",