chore(package): update dart-sass to version 1.17.0

Author: greenkeeper[bot]

package.json

@@ -12,7 +12,7 @@
   "devDependencies": {
     "autoprefixer": "9.4.7",
     "cssnano": "4.1.8",
-    "dart-sass": "1.16.1",
+    "dart-sass": "1.17.0",
     "fibers": "3.1.1",
     "grunt": "~1",
     "grunt-cli": "~1",