fix: add missing style-loader

Add missing style-loader package causing a silent error

Author: sghoweri

packages/uikit-workshop/package.json

@@ -59,6 +59,7 @@
     "postcss-loader": "^3.0.0",
     "raw-loader": "^0.5.1",
     "sass-loader": "^7.1.0",
+    "style-loader": "^0.23.1",
     "uglifyjs-webpack-plugin": "^1.2.7",
     "webpack": "4.16.3",
     "webpack-cli": "^3.1.0",