message: packages/core: added zen-observable dependency
diff: "react-router": "^5.2.0",
  "react-router-dom": "^5.2.0",
  "react-sparklines": "^1.7.0",
  - "react-syntax-highlighter": "^12.2.1"
  + "react-syntax-highlighter": "^12.2.1",
  + "zen-observable": "^0.8.15"
  },
  "devDependencies": {
  "@backstage/cli": "^0.1.1-alpha.5",
  "@types/jest": "^25.2.1",
  "@types/node": "^12.0.0",
  "@types/react-helmet": "^5.0.15",
  - "@types/react-sparklines": "^1.7.0"
  + "@types/react-sparklines": "^1.7.0",
  + "@types/zen-observable": "^0.8.0"
  },
  "files": [
  "dist"
  