fix: gorm.GormDataTypeInterface => gorm.GormDBDataTypeInterface

[zohu]

ERROR: type "datetime" does not exist

[kuafuRace]

I hope to keep the lightweight of carbon and not rely on third-party package. You can reimplement the interface through embedded types，such as

type DateTime struct {
    *carbon.Carbon
}
func (c *DateTime) GormDataType() string {
    //return "TIMESTAMP"
    //return "TEXT"
    return "DATETIME"
}

[zohu]

I hope to keep the lightweight of carbon and not rely on third-party package. You can reimplement the interface through embedded types，such as

type DateTime struct {
    *carbon.Carbon
}
func (c *DateTime) GormDataType() string {
    //return "TIMESTAMP"
    //return "TEXT"
    return "DATETIME"
}

I understand that this library is zero-dependency, so could you please avoid implementing GormDataType in the library? It may cause a panic if the GORM tag 'type' is not added.

[zohu]

keep this part consistent with v2.6.7?

[kuafuRace]

keep this part consistent with v2.6.7?保持此部分与v2.6.7一致？

Okay, next version will remove implementing GormDataType

[kuafuRace]

v2.6.9 has been released