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/_api/credentials/store.py

@@ -19,7 +19,7 @@ from . import constants, errors
 from .utils import create_environment_dict, find_executable
 
 
-class Store(object):
+class Store:
     def __init__(self, program, environment=None):
         """Create a store object that acts as an interface to
         perform the basic operations for storing, retrieving