Asynchronous identity_token_provider to WorkloadIdentityCredentials

I have an asynchronous application which uses Workload Identity Federation within AWS to communicate with the Anthropic API. The identity_token_provider function I provide to WorkloadIdentityCredentials needs to make a network call to the AWS STS to get a token. I would like to be able to provide an async function so that I can make that call in a way that is compatible with how the rest of my app works. That does not appear to be supported currently.