Drop python 3.7 support

[p1c2u]

No description provided.

[codecov]

Codecov Report

Merging #595 (3fbfdf5) into master (eaa0947) will decrease coverage by 0.09%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #595      +/-   ##
==========================================
- Coverage   90.38%   90.29%   -0.09%     
==========================================
  Files         127      127              
  Lines        3745     3711      -34     
  Branches      454      445       -9     
==========================================
- Hits         3385     3351      -34     
  Misses        303      303              
  Partials       57       57              

Impacted Files	Coverage Δ
openapi_core/contrib/requests/protocols.py	100.00% <100.00%> (ø)
openapi_core/protocols.py	78.00% <100.00%> (-1.63%)	⬇️
openapi_core/schema/protocols.py	83.33% <100.00%> (-4.17%)	⬇️
openapi_core/unmarshalling/request/protocols.py	78.94% <100.00%> (-3.67%)	⬇️
openapi_core/unmarshalling/response/protocols.py	81.81% <100.00%> (-2.80%)	⬇️
openapi_core/validation/request/protocols.py	73.91% <100.00%> (-3.87%)	⬇️
openapi_core/validation/response/protocols.py	75.00% <100.00%> (-3.58%)	⬇️
openapi_core/validation/schemas/validators.py	89.53% <100.00%> (-0.36%)	⬇️
openapi_core/validation/validators.py	94.39% <100.00%> (-0.16%)	⬇️