ModelPricing model.
@type t() :: %ExBifrost.Model.ModelPricing{ completion: String.t() | nil, image: String.t() | nil, input_cache_read: String.t() | nil, input_cache_write: String.t() | nil, internal_reasoning: String.t() | nil, prompt: String.t() | nil, request: String.t() | nil, web_search: String.t() | nil }