Python code modernization, 2/n (#1156)

* Adjust all __future__ imports:

for i in $(grep -REl "__future__.*absolute_import" plugins/ tests/); do
  sed -e 's/from __future__ import .*/from __future__ import annotations/g' -i $i;
done

* Remove all UTF-8 encoding specifications for Python source files:

for i in $(grep -REl '[-][*]- coding: utf-8 -[*]-' plugins/ tests/); do
  sed -e '/^# -\*- coding: utf-8 -\*-/d' -i $i;
done

* Reformat.

plugins/module_utils/_api/credentials/constants.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # This code is part of the Ansible collection community.docker, but is an independent component.
 # This particular file, and this file only, is based on the Docker SDK for Python (https://github.com/docker/docker-py/)
 #

plugins/module_utils/_api/credentials/errors.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # This code is part of the Ansible collection community.docker, but is an independent component.
 # This particular file, and this file only, is based on the Docker SDK for Python (https://github.com/docker/docker-py/)
 #

plugins/module_utils/_api/credentials/store.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # This code is part of the Ansible collection community.docker, but is an independent component.
 # This particular file, and this file only, is based on the Docker SDK for Python (https://github.com/docker/docker-py/)
 #

plugins/module_utils/_api/credentials/utils.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # This code is part of the Ansible collection community.docker, but is an independent component.
 # This particular file, and this file only, is based on the Docker SDK for Python (https://github.com/docker/docker-py/)
 #