isGhes() reads GITHUB_SERVER_URL and takes every host but github.com and
its enterprise ones for a GHES, where the v4 artifact backend is absent.
On Gitea that backend is there and answers, but the check runs on the
runner ahead of any request, so the upload never starts. It now returns
false. See GITEA-PATCH.md.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
