feat: deprecate sequelize.import usage

- https://sequelize.org/master/manual/models-definition.html
- #1579

Signed-off-by: Yukai Huang <yukaihuangtw@gmail.com>

Author: Yukaii

lib/models/index.js

@@ -45,7 +45,7 @@ fs.readdirSync(__dirname)
     return (file.indexOf('.') !== 0) && (file !== 'index.js')
   })
   .forEach(function (file) {
-    var model = sequelize.import(path.join(__dirname, file))
+    var model = require(path.join(__dirname, file))(sequelize, Sequelize)
     db[model.name] = model
   })