Update flake8 to 4.0.1

[pyup-bot]

This PR updates flake8 from 3.8.4 to 4.0.1.

Changelog

3.9.2

-------------------

You can view the `3.9.2 milestone`_ on GitHub for more details.

Bugs Fixed
~~~~~~~~~~

- Fix error message for ``E111`` in ``pycodestyle`` (See also :pull:`1328`,
:issue:`1327`).

Deprecations
~~~~~~~~~~~~

- ``indent_size_str`` is deprecated, use ``str(indent_size)`` instead (See
also :pull:`1328`, :issue:`1327`).


.. all links
.. _3.9.2 milestone:
 https://github.com/PyCQA/flake8/milestone/40

3.9.1

-------------------

You can view the `3.9.1 milestone`_ on GitHub for more details.

Bugs Fixed
~~~~~~~~~~

- Fix codes being ignored by plugins utilizing ``extend_default_ignore`` (See
also :pull:`1317`)


.. all links
.. _3.9.1 milestone:
 https://github.com/PyCQA/flake8/milestone/38

3.9.0

-------------------

You can view the `3.9.0 milestone`_ on GitHub for more details.

New Dependency Information
~~~~~~~~~~~~~~~~~~~~~~~~~~

- Pyflakes has been updated to >= 2.3.0, < 2.4.0 (See also :issue:`1006`)

- pycodestyle has been updated to >= 2.7.0, < 2.8.0 (See also :issue:`1007`)

Deprecations
~~~~~~~~~~~~

- Drop support for python 3.4 (See also :issue:`1283`)

Features
~~~~~~~~

- Add ``--no-show-source`` option to disable ``--show-source`` (See also
:issue:`995`)

Bugs Fixed
~~~~~~~~~~

- Fix handling of ``crlf`` line endings when linting stdin (See also
:issue:`1002`)


.. all links
.. _3.9.0 milestone:
 https://github.com/pycqa/flake8/milestone/37

Links

• PyPI: https://pypi.org/project/flake8
• Changelog: https://pyup.io/changelogs/flake8/
• Repo: https://github.com/pycqa/flake8

[codecov-commenter]

Codecov Report

Merging #23 (af25093) into master (1799b89) will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master     #23   +/-   ##
======================================
  Coverage    8.69%   8.69%           
======================================
  Files           3       3           
  Lines          23      23           
======================================
  Hits            2       2           
  Misses         21      21           

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[pyup-bot]

Closing this in favor of #32