feat: replace `%{?systemd_requires}` with `%{?systemd_ordering}`
As said [in the documentation](https://docs.fedoraproject.org/en-US/packaging-guidelines/Scriptlets/#_dependencies_on_the_systemd_package):
> If the package wants to use systemd tools if they are available, but does not
want to declare a dependency, then the `%{?systemd_ordering}` macro MAY be used
as a weaker form of %{?systemd_requires} that only declares an ordering during
an RPM transaction.
See https://github.com/systemd/systemd/commit/2424b6bd716f0c1c3bf3406b1fd1a16ba1b6a556
and https://pagure.io/packaging-committee/issue/644 for more information.
And also use `--setopt=install_weak_deps=False` to avoid installing a lot of
useless dependencies.
Julien Voisin