[pre-commit.ci] pre-commit autoupdate

[pre-commit-ci]

updates:

• github.com/PyCQA/flake8: 3.9.2 → 4.0.1

[CLAassistant]

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[codecov]

Codecov Report

Merging #197 (005379b) into master (78ed66f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #197   +/-   ##
=======================================
  Coverage   96.49%   96.49%           
=======================================
  Files          10       10           
  Lines         599      599           
=======================================
  Hits          578      578           
  Misses         21       21           

Flag	Coverage Δ
unittests	96.49% <ø> (ø)

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[zhiqwang]

LGTM