Upgrade yargs

Author: RyanZim

package.json

@@ -27,7 +27,7 @@
     "postcss-load-config": "^1.1.0",
     "postcss-reporter": "^3.0.0",
     "read-cache": "^1.0.0",
-    "yargs": "^7.0.2"
+    "yargs": "^8.0.1"
   },
   "devDependencies": {
     "ava": "^0.19.1",