CI: Enable EPEL Next

The ansible thing that installs packages does that one by one.

Hence, the assumption is that by installing epel-next-release first,
mock should be available next.

Resolves: rhbz#2065590

tests/tests.yml

@@ -89,6 +89,7 @@
         dir: .
         run: rpmbuild -ba escape_percentages.spec
     required_packages:
+    - epel-next-release
     - mock
     - rpmdevtools
     - rpm-build