copr-backend: install the latest copr-rpmbuild on builders

roles/copr/backend/files/provision/provision_builder_tasks.yml

@@ -33,7 +33,6 @@
     - ethtool
     - nosync
     - expect
-    - copr-rpmbuild-0.8
 
 - name: disable @copr/copr explicitly
   shell: dnf copr -y disable @copr/copr
@@ -46,7 +45,7 @@
     - ca-certificates
     - mock
     - dnf
-#    - copr-rpmbuild
+    - copr-rpmbuild
 
 - name: put updated mock configs into /etc/mock
   template: src=files/mock/{{ item }} dest=/etc/mock