fix: deps/v8/tools/clusterfuzz/js_fuzzer/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-FORMDATA-10841150

Author: snyk-bot

deps/v8/tools/clusterfuzz/js_fuzzer/package.json

@@ -23,7 +23,7 @@
   "devDependencies": {
     "eslint": "^6.8.0",
     "mocha": "^3.5.3",
-    "pkg": "^4.3.4",
+    "pkg": "^5.0.0",
     "prettier": "2.0.5",
     "sinon": "^4.0.0"
   },