Update dependency webpack-dev-server to v5

Author: mend-for-github-com[bot]

package.json

@@ -51,7 +51,7 @@
     "uglifyify": "^3.0.1",
     "vinyl-source-stream": "^1.0.0",
     "webpack": "^1.8.11",
-    "webpack-dev-server": "^1.8.2"
+    "webpack-dev-server": "^5.2.0"
   },
   "dependencies": {
     "classnames": "^2.2.0",