fix(mock-configs): use dnf

`dnf` is just `dnf5` in Fedora 41

ultramarine/ultramarine-mock-configs/ultramarine.tpl

@@ -4,7 +4,7 @@ config_opts['macros']['%dist'] = '.um{{ releasever }}'
 config_opts['macros']['%ultramarine'] = '{{ releasever }}'
 config_opts['chroot_setup_cmd'] = 'install @buildsys-build'
 config_opts['buildroot_pkgs'] = 'ultramarine-release ultramarine-release-basic'
-config_opts['package_manager'] = 'dnf5'
+config_opts['package_manager'] = 'dnf'
 config_opts['extra_chroot_dirs'] = [ '/run/lock', ]
 config_opts['mirrored'] = True
 config_opts['plugin_conf']['root_cache_enable'] = True