message: chore: add missing types field to jest-core package.json
diff: "description": "Delightful JavaScript Testing.",
  "version": "24.1.0",
  "main": "build/jest.js",
  + "types": "build/jest.d.ts",
  "dependencies": {
  "@jest/types": "^24.1.0",
  "@jest/reporters": "^24.1.0",
  