copr-be: make sure that obsrun group is available

roles/copr/backend/tasks/main.yml

@@ -5,6 +5,9 @@
 - name: setup networking
   import_tasks: "network.yml"
 
+- name: create obsrun group for `sign' command
+  group: name=obsrun
+
 # pre-create copr user and group with predefined uid and gid
 - group: name=copr gid=986
 - user: name=copr group=copr uid=989 groups=obsrun