Flake8 check fixes

[p1c2u]

No description provided.

[codecov]

Codecov Report

Merging #180 into master will decrease coverage by 0.17%.
The diff coverage is 72.22%.

@@            Coverage Diff             @@
##           master     #180      +/-   ##
==========================================
- Coverage   96.62%   96.45%   -0.18%     
==========================================
  Files          71       71              
  Lines        1721     1719       -2     
==========================================
- Hits         1663     1658       -5     
- Misses         58       61       +3

Impacted Files	Coverage Δ
openapi_core/schema/schemas/_types.py	100% <ø> (ø)	⬆️
openapi_core/schema/schemas/_format.py	85.29% <ø> (-4.42%)	⬇️
openapi_core/contrib/flask/responses.py	100% <ø> (ø)	⬆️
openapi_core/schema/schemas/exceptions.py	87.27% <ø> (ø)	⬆️
openapi_core/schema/schemas/factories.py	100% <ø> (ø)	⬆️
openapi_core/schema/parameters/exceptions.py	85.18% <0%> (ø)	⬆️
openapi_core/schema/media_types/exceptions.py	85.71% <0%> (ø)	⬆️
openapi_core/schema/content/exceptions.py	90% <0%> (ø)	⬆️
openapi_core/schema/responses/exceptions.py	86.66% <0%> (ø)	⬆️
openapi_core/schema/media_types/models.py	90.24% <100%> (ø)	⬆️
... and 5 more

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