style: remove not used pkg, close #185

Author: Scrum

package.json

@@ -58,7 +58,6 @@
     "coveralls": "^3.0.0",
     "eslint": "^4.15.0",
     "eslint-config-xo": "^0.19.0",
-    "eslint-formatter-pretty": "^1.1.0",
     "eslint-plugin-ava": "^4.0.1",
     "eslint-plugin-babel": "^4.0.1",
     "eslint-plugin-html": "^4.0.1",