fix can not find chunk in some case (#3)

*  resolve chunk canot find when chunk name like this "styles/test.css?db562740a398ac3c4f42e7d579e5b365"

* fix not find "some.css"

Author: gxlmyacc

lib/index.js

@@ -7,7 +7,7 @@ function CssChunkHashPlugin(options) {
 CssChunkHashPlugin.prototype.createCssHash = function ({ assetsByChunkName, publicPath }) {
   return Object.keys(assetsByChunkName).reduce((hash, name) => {
     if (!assetsByChunkName[name] || !assetsByChunkName[name].find) return hash;
-    const file = assetsByChunkName[name].find(file => file.endsWith('.css'));
+    const file = assetsByChunkName[name].find(file => file.indexOf('.css') >= 0 && file.indexOf('.css.map') < 0);
     if (file) hash[name] = `${publicPath}${file}`;
     return hash;
   }, {});