fix: rpm sign resource leak (#4878)
Fixed the resource leak in #4780.
Related: [go-gitea/gitea#31794](https://github.com/go-gitea/gitea/pull/31794)
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/4878
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Exploding Dragon <explodingfkl@gmail.com>
Co-committed-by: Exploding Dragon <explodingfkl@gmail.com>
authored by