Update dependency @nestjs/core to v6.0.3

Author: renovate-bot

package.json

@@ -20,7 +20,7 @@
   },
   "dependencies": {
     "@nestjs/common": "6.0.2",
-    "@nestjs/core": "6.0.2",
+    "@nestjs/core": "6.0.3",
     "@nestjs/microservices": "6.0.2",
     "@nestjs/platform-express": "6.0.2",
     "@nestjs/websockets": "6.0.2",