https://mongoosejs.com/docs/deprecations.html#findandmodify

mongoose.connect("mongodb://localhost/test1", { useNewUrlParser: true, useUnifiedTopology: true });
//test1 is databse name// Make Mongoose use `findOneAndUpdate()`. Note that this option is `true`
// by default, you need to set it to false.
mongoose.set('useFindAndModify', false);