Add more CI checks (#1150)

* Enable mypy.

* Add flake8.

* Add pylint with a long list of ignores to be removed.

plugins/module_utils/_common_cli.py

@@ -229,8 +229,6 @@ class AnsibleDockerClientBase(object):
             check_rc=True,
         )
         if tag:
-            lookup = f"{name}:{tag}"
-            lookup_digest = f"{name}@{tag}"
             response = images
             images = []
             for image in response: