Bump webpack-dev-server from 3.11.3 to 5.2.1 in /benchmarks/erubi-rails

Bumps [webpack-dev-server](https://github.com/webpack/webpack-dev-server) from 3.11.3 to 5.2.1.
- [Release notes](https://github.com/webpack/webpack-dev-server/releases)
- [Changelog](https://github.com/webpack/webpack-dev-server/blob/master/CHANGELOG.md)
- [Commits](webpack/webpack-dev-server@v3.11.3...v5.2.1)

---
updated-dependencies:
- dependency-name: webpack-dev-server
  dependency-version: 5.2.1
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

benchmarks/erubi-rails/package.json

@@ -12,6 +12,6 @@
   },
   "version": "0.1.0",
   "devDependencies": {
-    "webpack-dev-server": "^3"
+    "webpack-dev-server": "^5"
   }
 }