docker swarm - Add no_log to the signing_ca_key argument (#80)

* docker swarm - Add no_log to the signing_ca_key argument

This will prevent accidental disclosure.

See: CVE-2021-20191

* Update changelogs/fragments/CVE-2021-20191_no_log.yml

Co-authored-by: Felix Fontein <felix@fontein.de>

plugins/modules/docker_swarm.py

@@ -603,7 +603,7 @@ def main():
         name=dict(type='str'),
         labels=dict(type='dict'),
         signing_ca_cert=dict(type='str'),
-        signing_ca_key=dict(type='str'),
+        signing_ca_key=dict(type='str', no_log=True),
         ca_force_rotate=dict(type='int'),
         autolock_managers=dict(type='bool'),
         node_id=dict(type='str'),