fix: upgrade webpack-dev-server from 3.9.0 to 3.10.1 (#6)

Snyk has created this PR to upgrade webpack-dev-server from 3.9.0 to 3.10.1.

See this package in NPM:
https://www.npmjs.com/package/webpack-dev-server

See this project in Snyk:
https://app.snyk.io/org/alfill-github-marketplace/project/8d40a57b-18e0-4972-88ac-cdfb15b6e0b3?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -39,7 +39,7 @@
 		"style-loader": "^0.23.1",
 		"webpack": "^4.41.3",
 		"webpack-cli": "^3.1.2",
-		"webpack-dev-server": "^3.1.9",
+		"webpack-dev-server": "^3.10.1",
 		"workbox-webpack-plugin": "^3.6.2"
 	}
 }