Hardcoded createdAt field when using underscored option

[zignis]

Issue

Versions

• sequelize: latest
• sequelize-typescript: latest
• typescript: -

Issue type

• [x] bug report
• [ ] feature request

Actual behavior

Even when using the underscored option, typescript keeps complaining about .created_at field, because its hard-coded as createdAt here:

https://github.com/sequelize/sequelize-typescript/blob/62a0863051bd074243dab223eebf5e056aa46e0d/src/model/model/model.ts#L34

Expected behavior

Should be able to use created_at.

Steps to reproduce

Configure the table using the underscored option.