pub fn new_minimal(access_key: String, secret_access_key: String) -> StaticProvider {
        StaticProvider {
            credentials: AwsCredentials::new(access_key, secret_access_key, None, None),
            valid_for: None,
        }
    }
Creates a new minimal Static Provider. This will set the token as optional none.
rusoto/credential/src/static_provider.rs