Updated AdCreativeFeaturesSpec with new image_brightness_and_contrast field

[Just1B]

Checklist

• [x] I've read the Contributing Guidelines and the Code of Conduct
• [x] I've completed the Contributor License Agreement

Pull Request Details

Updated AdCreativeFeaturesSpec adobject with new image_brightness_and_contrast field based on API responses observation

The Field does not appear in the documentation -> https://developers.facebook.com/docs/marketing-api/reference/ad-creative-features-spec/

First time seeing this field in my system : 2024-04-25