{CI} Make .flake8 compatible with Flake8 6.0.0

[bebound]

Description

In Azure/azure-cli-dev-tools#351, Flake8 is upgrade to 6.0, and the old .flake8 is not compatible.

Flake8 does not support inline comments for any of the keys -- https://flake8.pycqa.org/en/6.0.0/user/configuration.html

I put comments to new lines.

Without this PR, this error is raised.

╰─ azdev style redis                                                                                                                        ─╯

===============
| Style Check |
===============

Modules: redis

Running pylint on modules...
Pylint: PASSED

Running flake8 on modules...
Traceback (most recent call last):
  File "C:\Users\kk\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\kk\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\kk\Developer\azure-cli\venv\lib\site-packages\flake8\__main__.py", line 7, in <module>
    raise SystemExit(main())
  File "C:\Users\kk\Developer\azure-cli\venv\lib\site-packages\flake8\main\cli.py", line 23, in main
    app.run(argv)
  File "C:\Users\kk\Developer\azure-cli\venv\lib\site-packages\flake8\main\application.py", line 198, in run
    self._run(argv)
  File "C:\Users\kk\Developer\azure-cli\venv\lib\site-packages\flake8\main\application.py", line 186, in _run
    self.initialize(argv)
  File "C:\Users\kk\Developer\azure-cli\venv\lib\site-packages\flake8\main\application.py", line 165, in initialize
    self.plugins, self.options = parse_args(argv)
  File "C:\Users\kk\Developer\azure-cli\venv\lib\site-packages\flake8\options\parse_args.py", line 53, in parse_args
    opts = aggregator.aggregate_options(option_manager, cfg, cfg_dir, rest)
  File "C:\Users\kk\Developer\azure-cli\venv\lib\site-packages\flake8\options\aggregator.py", line 30, in aggregate_options
    parsed_config = config.parse_config(manager, cfg, cfg_dir)
  File "C:\Users\kk\Developer\azure-cli\venv\lib\site-packages\flake8\options\config.py", line 131, in parse_config
    raise ValueError(
ValueError: Error code 'W504#' supplied to 'ignore' option does not match '^[A-Z]{1,3}[0-9]{0,3}$'

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[yonzhan]

CI