chore(package): update style-loader to version 0.21.0

Author: greenkeeper[bot]

package.json

@@ -25,7 +25,7 @@
     "node-sass": "4.8.3",
     "postcss-loader": "2.1.4",
     "sass-loader": "7.0.1",
-    "style-loader": "0.20.3",
+    "style-loader": "0.21.0",
     "stylelint": "9.2.0",
     "stylelint-order": "0.8.1",
     "stylelint-scss": "3.0.1",