Bump webpack-dev-middleware and webpack-dev-server in /client

Removes [webpack-dev-middleware](https://github.com/webpack/webpack-dev-middleware). It's no longer used after updating ancestor dependency [webpack-dev-server](https://github.com/webpack/webpack-dev-server). These dependencies need to be updated together.


Removes `webpack-dev-middleware`

Updates `webpack-dev-server` from 3.11.3 to 5.0.4
- [Release notes](https://github.com/webpack/webpack-dev-server/releases)
- [Changelog](https://github.com/webpack/webpack-dev-server/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack/webpack-dev-server/compare/v3.11.3...v5.0.4)

---
updated-dependencies:
- dependency-name: webpack-dev-middleware
  dependency-type: indirect
- dependency-name: webpack-dev-server
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

client/package.json

@@ -83,7 +83,7 @@
         "url-loader": "^4.1.0",
         "webpack": "^4.43.0",
         "webpack-cli": "^3.3.11",
-        "webpack-dev-server": "^3.11.0",
+        "webpack-dev-server": "^5.0.4",
         "webpack-merge": "^4.2.2"
     },
     "browserslist": {