refactor: remove unused object-assign

Author: alexander-akait

lib/processCss.js

@@ -6,7 +6,6 @@ var formatCodeFrame = require("babel-code-frame");
 var Tokenizer = require("css-selector-tokenizer");
 var postcss = require("postcss");
 var loaderUtils = require("loader-utils");
-var assign = require("object-assign");
 var getLocalIdent = require("./getLocalIdent");
 
 var icssUtils = require('icss-utils');