`stdout_callback = yaml` -> `result_format = yaml`

Fixes:

> [DEPRECATION WARNING]: community.general.yaml has been deprecated. The plugin has been superseded by the the option `result_format=yaml` in callback plugin ansible.builtin.default from ansible-core 2.13 onwards. This feature will be removed from
community.general in version 13.0.0. Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.

Ref:

- https://docs.ansible.com/ansible/latest/collections/community/general/yaml_callback.html
- https://docs.ansible.com/ansible/latest/collections/ansible/builtin/default_callback.html#parameter-result_format

ansible.cfg

@@ -1,6 +1,6 @@
 [defaults]
 retry_files_enabled = False
-stdout_callback = yaml
+result_format = yaml
 
 [connection]
 pipelining = True