Update webpack.config.js

Author: dmitry-kurmanov

webpack.config.js

@@ -11,7 +11,7 @@ var packageJson = require("./package.json");
 
 var copyright = [
   "surveyjs-widgets - Widgets for the SurveyJS library v" + packageJson.version,
-  "Copyright (c) 2015-2017 Devsoft Baltic OÜ  - http://surveyjs.io/",
+  "Copyright (c) 2015-2019 Devsoft Baltic OÜ  - http://surveyjs.io/",
   "License: MIT (http://www.opensource.org/licenses/mit-license.php)"
 ].join("\n");