Bump webpack-dev-server from 3.1.4 to 3.1.11 (#20)

Bumps [webpack-dev-server](https://github.com/webpack/webpack-dev-server) from 3.1.4 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@v3.1.4...v3.1.11)

Author: dependabot[bot]

package.json

@@ -70,7 +70,7 @@
     "tslint-config-standard": "^7.1.0",
     "tslint-react": "^3.6.0",
     "typescript": "^2.9.2",
-    "webpack-dev-server": "3.1.4"
+    "webpack-dev-server": "3.1.11"
   },
   "homepage": "https://beeequeue.github.io/mob-timer",
   "husky": {