Update dependency webpack-dev-server to v3.11.2

Author: renovate-bot

package.json

@@ -106,7 +106,7 @@
     "terser-webpack-plugin": "1.4.1",
     "webpack": "4.39.1",
     "webpack-cli": "3.3.6",
-    "webpack-dev-server": "3.7.2",
+    "webpack-dev-server": "3.11.2",
     "webpack-merge": "4.2.1"
   }
 }