[#40644][Python] Support max_batch_weight in BatchElements and honor element_size_fn in stateful and keyed RunInference batching - #40682

On November 2, 2026, GitHub will restrict `pull_request_target` on public repositories by default. To continue allowing the event trigger, configure an Actions policy. Learn more: https://gh.io/securely-using-pull_request_target#default-policy-for-pull_request_target