examples(@nestjs) update plain mongoose example

Author: kamilmysliwiec

examples/06-mongoose/package.json

@@ -14,7 +14,7 @@
     "@nestjs/microservices": "^4.3.0",
     "@nestjs/testing": "^4.3.0",
     "@nestjs/websockets": "^4.3.0",
-    "mongoose": "^4.11.13",
+    "mongoose": "^5.0.1",
     "redis": "^2.7.1",
     "reflect-metadata": "^0.1.10",
     "rxjs": "^5.4.3",