Update to use 'joi' package (#111)

Author: valtlfelipe

lib/index.js

@@ -1,5 +1,7 @@
-const Joi = require('@hapi/joi');
-const { assert } = require('@hapi/hoek');
+const Joi = require('joi');
+const {
+    assert
+} = require('@hapi/hoek');
 const Schema = require('./schema');
 const Models = require('./models');
 const DB = require('./DB');

lib/schema.js

@@ -1,4 +1,4 @@
-const Joi = require('@hapi/joi');
+const Joi = require('joi');
 const Sequelize = require('sequelize');
 
 const option = Joi.object().keys({