[rpmbuild] install dnf-utils instead of yum-utils on Fedora
The yum-utils is provided by dnf-utils nowadays on Fedora, while
the original yum-utils package was not removed from F30
repositories, and is not installable:
- package dnf-utils-4.0.6-1.fc30.noarch conflicts with yum-utils
< 1.1.31-530 provided by yum-utils-1.1.31-519.fc30.noarch -