chore(package): update yargs to version 12.0.1

Author: greenkeeper[bot]

package.json

@@ -77,7 +77,7 @@
     "typescript": "^2.7.2",
     "webpack": "^4.1.1",
     "webpack-cli": "2.1.1",
-    "yargs": "^11.0.0"
+    "yargs": "^12.0.1"
   },
   "dependencies": {
     "http-server": "^0.11.1"