CI: Build on EPEL 10 and 9

I'd like the see passing a RHEL 9 build in the CI results when I push
a fix for it in the previous commit.

I named the EPEL versions explicitly because:

- I'm not sure we aspire for compatibility with RHEL 8. At least we did
  not do than in the rpmgit-overlays/COPR CI.
- epel-all would build for all minor EPEL version (e.g. 10.2, 10.2,
  10.0). I think it would be unnecessary.

CI tests are not run on EPELs because of these unrelated bugs that
should be fixed later:

- EPEL 10: computed "centos:stream:10" label is not a valid container name.
- EPEL 9:
  <https://download.copr.fedorainfracloud.org/results/rpmsoftwaremanagement/dnf-nightly/fedora-9-x86_64/repodata/repomd.xml>
  returns HTTP 404 error for
  copr:copr.fedorainfracloud.org:rpmsoftwaremanagement:dnf-nightly
  repository. Something miscomputes the URL ("epel" vs. "fedora").

Author: ppisar

.packit.yaml

@@ -13,13 +13,16 @@ jobs:
   - job: copr_build
     trigger: pull_request
     targets:
+      - epel-9
+      - epel-10
       - fedora-all
     additional_repos:
       - "copr://rpmsoftwaremanagement/dnf-nightly"
   - job: tests
     trigger: pull_request
     identifier: "dnf-tests"
     targets:
+      # EPELs fail now for unrelated reasons
       - fedora-all
     fmf_url: https://github.com/rpm-software-management/ci-dnf-stack.git
     fmf_ref: enable-tmt-dnf-4-stack