I mean, yes, Scarlett Johansson is the actress, but she is not playing herself in the movie. I didn't watch the movie, but I guess she matched her voice to the character, an AI called Samantha, who is not Scarlett Johansson.
It is not like the "Midler vs Ford" case that is often referred to. Where Ford hired a singer to sound like Midler, but that's Midler singing as Midler, not acting a fictional character.
Maybe Warner Bros could complain, they are the owners of the character OpenAI imitates. In the same way that Disney (rather than Scarlett Johansson) would complain if someone used the Black Widow character without permission.