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

Closes #271

Author: greenkeeper[bot]

package.json

@@ -107,7 +107,7 @@
     "react-icons": "^2.2.7",
     "rimraf": "^2.6.2",
     "sinon": "^4.4.2",
-    "style-loader": "^0.19.1",
+    "style-loader": "^0.21.0",
     "stylelint": "^8.4.0",
     "stylelint-config-recess-order": "^1.2.3",
     "stylelint-config-standard": "^18.1.0",