Fixing some yaml-lint warnings

Scope of this commit is to fix warnings reported by
offline-installer-master-yaml-lint jenkins job

Change-Id: Id858a37ce35d53ad1ffd5e5797607faae484ed15
Issue-ID: OOM-1753
Signed-off-by: Michal Ptacek <m.ptacek@partner.samsung.com>
diff --git a/ansible/infrastructure.yml b/ansible/infrastructure.yml
index 83e185f..18290ae 100644
--- a/ansible/infrastructure.yml
+++ b/ansible/infrastructure.yml
@@ -20,6 +20,8 @@
   roles:
     - docker
   tasks:
-    - import_tasks: roles/certificates/tasks/upload_root_ca.yml
+    - include_role:
+        name: certificates
+        tasks_from: upload_root_ca.yml
       vars:
         certificates_local_dir: certs