Update dependency yargs to v12.0.5

Author: renovate-bot

packages/graphqlgen/package.json

@@ -47,7 +47,7 @@
     "reason": "3.3.4",
     "rimraf": "2.6.2",
     "typescript": "3.1.6",
-    "yargs": "12.0.4"
+    "yargs": "12.0.5"
   },
   "devDependencies": {
     "@types/camelcase": "4.1.0",