Update dependency webpack-dev-server to v3.8.2

Author: renovate-bot

package.json

@@ -66,7 +66,7 @@
     "url-loader": "1.1.2",
     "webpack": "4.30.0",
     "webpack-cli": "3.3.0",
-    "webpack-dev-server": "3.3.1",
+    "webpack-dev-server": "3.8.2",
     "webpack-serve": "3.1.0"
   }
 }