Python code modernization, 3/n (#1157)

* Remove __metaclass__ = type.

for i in $(grep -REl '__metaclass__ = type' plugins/ tests/); do
  sed -e '/^__metaclass__ = type/d' -i $i;
done

* Remove super arguments, and stop inheriting from object.

plugins/modules/docker_image_push.py

@@ -97,7 +97,7 @@ from ansible_collections.community.docker.plugins.module_utils._util import (
 
 class ImagePusher(DockerBaseClass):
     def __init__(self, client):
-        super(ImagePusher, self).__init__()
+        super().__init__()
 
         self.client = client
         self.check_mode = self.client.check_mode