Fix keepcache values of yum_repository (#7506)

As the official document[1], the parameter keepcache should be
'0' or '1' as string. To avoid the following warning message,
this fixes the parameter value:

  [WARNING]: The value False (type bool) in a string field was
  converted to u'False' (type string). If this does not look
  like what you expect, quote the entire value to ensure it
  does not change.

https://docs.ansible.com/ansible/latest/collections/ansible/builtin/yum_repository_module.html

roles/container-engine/cri-o/tasks/crio_repo.yml

@@ -78,7 +78,7 @@
     baseurl: http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/CentOS_$releasever/
     gpgcheck: yes
     gpgkey: http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/CentOS_$releasever/repodata/repomd.xml.key
-    keepcache: false
+    keepcache: '0'
   when: ansible_distribution in ["CentOS"]
 
 - name: Add CRI-O kubic yum repo
@@ -97,7 +97,7 @@
     baseurl: http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/CentOS_7/
     gpgcheck: yes
     gpgkey: http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/CentOS_7/repodata/repomd.xml.key
-    keepcache: false
+    keepcache: '0'
   when: ansible_distribution in ["Amazon"]
 
 - name: Add CRI-O kubic yum repo