fix(package): update yargs to version 12.0.1 (#31)

Author: greenkeeper[bot]

package.json

@@ -83,7 +83,7 @@
     "tslint": "^5.10.0",
     "typescript": "2.7.2",
     "uglify-js": "^3.4.1",
-    "yargs": "^11.0.0"
+    "yargs": "^12.0.1"
   },
   "release": {
     "branch": "master",