CVE-2026-54673: electron-updater: Cross-origin redirect leaks `PRIVATE-TOKEN` and mixed-case `Authorization` credentials in `builder-util-runtime`

In electron-builder’s builder-util-runtime package, the HTTP redirect handler (HttpExecutor.prepareRedirectUrlOptions) only stripped a credential header whose key string matched exactly lowercase "authorization". Other credential-bearing headers — most notably PRIVATE-TOKEN (used by GitLab’s personal access token flow) and mixed-case Authorization (used by GitLab’s Bearer/OAuth flow) — were not stripped and could be forwarded to an attacker-controlled cross-origin redirect destination.