[skip-ci] RPM: bats requirement only on Fedora

The bats package is not available on RHEL. It's in Fedora and EPEL.

Having bats as a requirement for the `skopeo-tests` subpackage will
cause installibility test failures for RHEL 10 / C10S gating tests.

This commit makes `bats` a requirement only on Fedora. RHEL and CentOS
Stream gating will need to fetch bats through separately enabling EPEL
or other means.

Podman PR with similar change: containers/podman#22632

Signed-off-by: Lokesh Mandvekar <lsm5@redhat.com>

rpm/skopeo.spec

@@ -81,7 +81,9 @@ registries without the need to pull them
 Summary: Tests for %{name}
 
 Requires: %{name} = %{epoch}:%{version}-%{release}
+%if %{defined fedora}
 Requires: bats
+%endif
 Requires: gnupg
 Requires: jq
 Requires: golang