Remove autoprefixer from dev dependencies

Author: mrmrs

package.json

@@ -17,7 +17,6 @@
   },
   "dependencies": {},
   "devDependencies": {
-    "autoprefixer": "^6.0.3",
     "browser-sync": "^2.9.11",
     "css": "^2.1.0",
     "css-mqpacker": "^4.0.0",