Swift updates fail when Bitbucket binary artifacts redirect to blocked S3 host #324

What happened

A GitHub-managed Dependabot version update for the swift ecosystem fails while resolving a package graph that includes Usercentrics Swift packages hosted on Bitbucket. The Bitbucket Git metadata and source fetches succeed. When SwiftPM downloads the packages' .xcframework.zip binary artifacts, Bitbucket responds with HTTP 302 to bbuseruploads.s3.amazonaws.com; Dependabot's egress proxy logs that host as not allowlisted and returns HTTP 403. SwiftPM then reports badResponseStatusCode(403), and the update job exits with status 1.

Expected behavior

The updater should either support fetching binary artifacts from this redirected host, or provide a documented configuration/workaround for package registries and artifact hosts that use redirects.

Impact

The failure can prevent updates to other dependencies in the same Swift package graph because SwiftPM resolves the package and fetches its binary targets as part of the update. Ignoring Usercentrics version updates does not appear to avoid resolving the declared packages and their binary artifacts.

Minimal reproduction

1. Configure a GitHub-managed Dependabot swift update for a package whose manifest depends on a Bitbucket-hosted Swift package.
2. The Bitbucket package declares one or more remote binaryTarget artifacts served from Bitbucket Downloads.
3. Run a version update. Git fetches from Bitbucket succeed, but the artifact download redirects to bbuseruploads.s3.amazonaws.com and is rejected by the updater proxy with HTTP 403 (egress not allowlisted).

Question

Is this host intentionally blocked for Dependabot jobs? What is the supported way to make SwiftPM binary artifacts behind this Bitbucket redirect available to GitHub-managed Dependabot? If the egress allowlist is managed outside dependabot-core, please point to the appropriate support path or documentation.