Update repo.sls

In order to work with salt-ssh.
Otherwise: "- Rendering SLS 'base:linux.system.repo' failed: found unexpected ':'" fail message

linux/system/repo.sls

@@ -216,7 +216,7 @@ default_repo_list:
     - replace: True
     {%- endif %}
     - defaults:
-        default_repos: {{ default_repos }}
+        default_repos: {{ default_repos|yaml }}
 
   {%- endif %}