Bump webpack-dev-server from 3.1.8 to 3.1.11

Bumps [webpack-dev-server](https://github.com/webpack/webpack-dev-server) from 3.1.8 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@v3.1.8...v3.1.11)

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

package.json

@@ -56,6 +56,6 @@
     "typescript": "3.0.3",
     "webpack": "4.17.2",
     "webpack-cli": "3.1.0",
-    "webpack-dev-server": "3.1.8"
+    "webpack-dev-server": "3.1.11"
   }
 }