fix: contracts/zero-ex/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/npm:debug:20170905

contracts/zero-ex/package.json

@@ -57,15 +57,15 @@
         "@0x/contracts-gen": "^2.0.10",
         "@0x/contracts-erc20": "^3.2.1",
         "@0x/contracts-test-utils": "^5.3.4",
-        "@0x/dev-utils": "^3.3.0",
+        "@0x/dev-utils": "^5.0.0",
         "@0x/order-utils": "^10.3.0",
         "@0x/sol-compiler": "^4.1.1",
         "@0x/ts-doc-gen": "^0.0.22",
         "@0x/tslint-config": "^4.1.0",
         "@types/lodash": "4.14.104",
         "@types/mocha": "^5.2.7",
         "lodash": "^4.17.11",
-        "mocha": "^6.2.0",
+        "mocha": "^8.3.0",
         "npm-run-all": "^4.1.2",
         "shx": "^0.2.2",
         "solhint": "^1.4.1",
@@ -76,7 +76,7 @@
     },
     "dependencies": {
         "@0x/base-contract": "^6.2.3",
-        "@0x/subproviders": "^6.1.1",
+        "@0x/subproviders": "^7.0.0",
         "@0x/types": "^3.2.0",
         "@0x/typescript-typings": "^5.1.1",
         "@0x/utils": "^5.5.1",