fix(ci): drop sudo from dnf install (runner runs as root, no sudo)

The act runner container has no sudo binary; the runner user already
runs as root inside the container. Existing steps (rpmbuild, gpg, etc)
already invoke privileged commands directly without sudo.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitea/workflows/build-prerelease.yml

@@ -123,7 +123,7 @@ jobs:
         run: |
           set -eux
           if ! command -v cargo >/dev/null 2>&1; then
-            sudo dnf install -y --setopt=install_weak_deps=False rust cargo clippy
+            dnf install -y --setopt=install_weak_deps=False rust cargo clippy
           fi
           cargo --version