build: remove engine from package.json

Author: kamilogorek

package.json

@@ -24,10 +24,6 @@
     "test:typescript": "tsc --noEmit --noImplicitAny typescript/raven-tests.ts",
     "test:ci": "npm run lint && grunt test:ci"
   },
-  "engines": {
-    "node": "^8.4.0",
-    "npm": "^5.4.0"
-  },
   "devDependencies": {
     "bluebird": "^3.4.1",
     "browserify-versionify": "^1.0.6",