message: fix: update cross-fetch to v3.0.6
diff: "url": "https://github.com/blockstack/blockstack.js/issues"
  },
  "dependencies": {
  - "cross-fetch": "^3.0.5"
  + "cross-fetch": "^3.0.6"
  },
  "devDependencies": {
  "@types/jest": "^24.9.0",
  