CI: Install EPEL packages first

For unknown reason, packages from required_packages were installed in seemingly arbitrary order.

This lead to errors like:

    No match for argument: tox

As tox was trying to be installed before epel.

Or:

    Problem: conflicting requests
      - nothing provides epel-release = 9-10.el9 needed by epel-next-release-9-10.el9.noarch from @commandline

As epel-next-release was trying to be installed before epel.

Let's prefix everything with epel installation. One by one, in the required order.

Related: RHEL-168159, RHEL-167917

tests/tests.yml

@@ -6,6 +6,12 @@
     - dnf:
         name: "*"
         state: latest
+    - dnf:
+        name: "https://dl.fedoraproject.org/pub/epel/epel-release-latest-9.noarch.rpm"
+        state: installed
+    - dnf:
+        name: "https://dl.fedoraproject.org/pub/epel/epel-next-release-latest-9.noarch.rpm"
+        state: installed
 
 - hosts: localhost
   roles:
@@ -47,8 +53,6 @@
         dir: python/marshalparser
         run: "VERSION={{ pybasever }} SAMPLE=10 test_marshalparser_compatibility.sh"
     required_packages:
-    - 'https://dl.fedoraproject.org/pub/epel/epel-release-latest-9.noarch.rpm'
-    - 'https://dl.fedoraproject.org/pub/epel/epel-next-release-latest-9.noarch.rpm'
     - gcc  # for extension building in venv and selftest
     - gcc-c++ # for test_cppext
     - gdb  # for test_gdb