examples(@nestjs) update plain mongoose example

Author: kamilmysliwiec

examples/06-mongoose/src/database/database.providers.ts

@@ -3,11 +3,7 @@ import * as mongoose from 'mongoose';
 export const databaseProviders = [
   {
     provide: 'DbConnectionToken',
-    useFactory: async (): Promise<mongoose.Connection> => {
-      (mongoose as any).Promise = global.Promise;
-      return await mongoose.connect('mongodb://localhost/nest', {
-        useMongoClient: true,
-      });
-    },
+    useFactory: async (): Promise<mongoose.Connection> =>
+      await mongoose.connect('mongodb://localhost/nest'),
   },
 ];