Improving yamllint configuration (#11389)

Signed-off-by: Bas Meijer <bas.meijer@enexis.nl>

roles/download/tasks/prep_download.yml

@@ -69,7 +69,7 @@
   file:
     path: "{{ local_release_dir }}/images"
     state: directory
-    mode: 0755
+    mode: "0755"
     owner: "{{ ansible_ssh_user | default(ansible_user_id) }}"
   when:
     - ansible_os_family not in ["Flatcar", "Flatcar Container Linux by Kinvolk"]
@@ -78,7 +78,7 @@
   file:
     path: "{{ download_cache_dir }}/images"
     state: directory
-    mode: 0755
+    mode: "0755"
   delegate_to: localhost
   connection: local
   delegate_facts: no