chore(package): update sass-loader to version 8.0.0

Author: greenkeeper[bot]

package.json

@@ -97,7 +97,7 @@
     "react-test-renderer": "16.9.0",
     "request": "2.87.0",
     "request-promise": "4.2.4",
-    "sass-loader": "7.3.1",
+    "sass-loader": "8.0.0",
     "style-loader": "1.0.0",
     "svg-prep": "1.0.4",
     "webpack": "4.39.3",