nginx image “stable” tag points to mainline (1.27.x) instead of even-numbered stable branch

### Which image/versions are related to this issue/feature request? I noticed that in the cgr.dev/chainguard/nginx repository: - The stable tag currently resolves to 1.27.x, which is an odd-numbered mainline release. - The latest tag resolves to 1.28.x, the even-numbered stable release. This inverts the community convention used by the official NGINX Docker images, where: - stable → latest even-numbered minor (e.g. 1.26.x → 1.28.x…) - latest → mainline (odd-numbered minor) See: - https://github.com/nginx/nginx/branches/all?query=stable- - https://images.chainguard.dev/directory/image/nginx/versions ### Issue/Feature description fix issue pls