Add support check mode for all info modules

As it's required by new ansible-test rules.
See https://github.com/ansible-collections/overview/issues/45#issuecomment-893543025
Change-Id: Ib6b73e810b972997b8de2b4a9eb8e07e246823d5

plugins/modules/keypair_info.py

@@ -115,6 +115,9 @@ class KeyPairInfoModule(OpenStackModule):
         limit=dict(type='int', required=False),
         marker=dict(type='str', required=False)
     )
+    module_kwargs = dict(
+        supports_check_mode=True
+    )
 
     def run(self):
         name = self.params['name']