Update dependency webpack to v5

Author: renovate[bot]

package.json

@@ -46,7 +46,7 @@
     "react-dom": "^15.4.1",
     "react-event-listener": "^0.4.5",
     "react-styleguidist": "^4.4.1",
-    "webpack": "^2.6.1",
+    "webpack": "^5.0.0",
     "webpack-dev-server": "^2.4.5"
   },
   "dependencies": {