take out engines

package.json

@@ -3,10 +3,6 @@
   "version": "1.8.0",
   "description": "Heroku CLI plugin for Heroku CI",
   "main": "index.js",
-  "engines": {
-    "node": ">=6.8.1 <8.0.0",
-    "npm": ">=3.10.8"
-  },
   "scripts": {
     "test": "mocha -R tap && standard --verbose | standard-tap",
     "format": "standard --format"