Bump webpack-dev-server from 2.9.3 to 3.1.3

Bumps [webpack-dev-server](https://github.com/webpack/webpack-dev-server) from 2.9.3 to 3.1.3.
- [Release notes](https://github.com/webpack/webpack-dev-server/releases)
- [Commits](webpack/webpack-dev-server@v2.9.3...v3.1.3)

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

Author: dependabot-support

package.json

@@ -63,7 +63,7 @@
     "vue-server-renderer": "^2.5.13",
     "vue-template-compiler": "^2.5.13",
     "webpack": "^3.8.1",
-    "webpack-dev-server": "^2.9.3"
+    "webpack-dev-server": "^3.1.3"
   },
   "pre-commit": [
     "lint"