MongooseError: Operation `users.insertOne()` buffering timed out after 10000ms

Hi @diegohaz ,
I congratulate you on the project.

I have performed the given steps but am having trouble getting it to work when I try to enter a user using the `MASTER_KEY` I get the following error:

> MongooseError: Operation `users.insertOne ()` buffering timed out after 10000ms

From what I understand maybe it seems there are problems with the new versions:
https://mongoosejs.com/docs/deprecations.html(mongoose version 5.11.9)

A similar problem I also get with the findOne:
> Unhandled rejection MongooseError: Operation `users.findOne()` buffering timed out after 10000ms

You could give it a try, to see if it's my problem if I'm doing something wrong.

Link: [Github](https://github.com/Angelk90/api.store)

devDependencies:
```json
"devDependencies": {
"apidoc": "^0.20.0",
"apidoc-markdown": "^0.2.1",
"babel-eslint": "^10.1.0",
"babel-jest": "^25.1.0",
"cross-env": "^7.0.2",
"dotenv-safe": "^8.2.0",
"eslint": "^6.8.0",
"eslint-config-standard": "^14.1.0",
"eslint-plugin-import": "^2.20.0",
"eslint-plugin-node": "^11.0.0",
"eslint-plugin-promise": "^4.2.0",
"eslint-plugin-standard": "^4.0.1",
"jest-cli": "^25.1.0",
"mongodb-memory-server": "^6.3.3",
"nock": "^12.0.2",
"nodemon": "^2.0.2",
"open-cli": "^6.0.0",
"sinon": "^4.0.1",
"supertest": "^4.0.2"
},
"dependencies": {
"@babel/core": "^7.8.4",
"@babel/plugin-proposal-export-default-from": "^7.8.3",
"@babel/plugin-transform-runtime": "^7.8.3",
"@babel/preset-env": "^7.8.4",
"@babel/register": "^7.8.3",
"@babel/runtime": "^7.8.4",
"bcrypt": "^4.0.1",
"bluebird": "^3.7.2",
"body-parser": "^1.19.0",
"bodymen": "^1.1.1",
"compression": "^1.7.4",
"cors": "^2.8.5",
"express": "^4.17.1",
"express-force-ssl": "^0.3.2",
"jsonwebtoken": "^8.5.1",
"mongoose": "^5.9.4",
"mongoose-keywords": "^0.4.0",
"morgan": "^1.9.1",
"passport": "^0.4.1",
"passport-http": "^0.3.0",
"passport-http-bearer": "^1.0.1",
"passport-jwt": "^4.0.0",
"querymen": "^2.1.4",
"rand-token": "^0.4.0",
"request": "^2.88.2",
"request-promise": "^4.2.5"
}
```