chore(package): update sass-loader to version 7.0.1

Closes #9

Author: greenkeeper[bot]

package.json

@@ -84,7 +84,7 @@
     "prop-types": "^15.6.0",
     "react-dom": "^16.2.0",
     "react-test-renderer": "^16.2.0",
-    "sass-loader": "^6.0.6",
+    "sass-loader": "^7.0.1",
     "style-loader": "^0.20.0",
     "tslint": "^5.8.0",
     "tslint-eslint-rules": "^4.1.1",