Update package.json

Author: app-generator

react-ui/package.json

@@ -6,7 +6,7 @@
     "license": "See license in https://www.creative-tim.com/license",
     "description": "Material UI version of Soft UI Dashboard by Creative Tim",
     "build": {
-        "yarn": "v12.0.0",
+        "yarn": "v14.0.0,v16.0.0",
         "npm": "v14.0.0,v16.0.0"
     },    
     "bugs": {