Bump webpack-dev-server from 2.7.1 to 3.1.11

Bumps [webpack-dev-server](https://github.com/webpack/webpack-dev-server) from 2.7.1 to 3.1.11.
- [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@v2.7.1...v3.1.11)

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

Author: dependabot[bot]

package.json

@@ -69,7 +69,7 @@
     "typescript": "^3.0",
     "url-loader": "0.5.9",
     "webpack": "3.5.1",
-    "webpack-dev-server": "2.7.1",
+    "webpack-dev-server": "3.1.11",
     "webpack-manifest-plugin": "1.2.1",
     "whatwg-fetch": "2.0.3",
     "worker-loader": "^2.0.0"