Add isort and flake8 to CI (#869)

* Run isort.

* Clean up unused assignments.

* Add flake8 linting step.

plugins/modules/ecs_domain.py

@@ -6,6 +6,8 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 from __future__ import absolute_import, division, print_function
+
+
 __metaclass__ = type
 
 
@@ -224,12 +226,11 @@ import time
 
 from ansible.module_utils.basic import AnsibleModule
 from ansible.module_utils.common.text.converters import to_native
-
 from ansible_collections.community.crypto.plugins.module_utils.ecs.api import (
-    ecs_client_argument_spec,
     ECSClient,
     RestOperationException,
     SessionConfigurationException,
+    ecs_client_argument_spec,
 )
 
 
@@ -319,7 +320,7 @@ class EcsDomain(object):
                 return False
 
             return True
-        except RestOperationException as dummy:
+        except RestOperationException:
             return False
 
     def request_domain(self, module):