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/module_utils/_image_archive.py

@@ -12,7 +12,7 @@ import os
 import tarfile
 
 
-class ImageArchiveManifestSummary(object):
+class ImageArchiveManifestSummary:
     """
     Represents data extracted from a manifest.json found in the tar archive output of the
     "docker image save some:tag > some.tar" command.