Use openapi-schema-validator library

[p1c2u]

Schema validation moved to separate openapi-schema-validator library

[codecov]

Codecov Report

Merging #212 into master will increase coverage by 0.19%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #212      +/-   ##
==========================================
+ Coverage   96.52%   96.71%   +0.19%     
==========================================
  Files         123      118       -5     
  Lines        2477     2317     -160     
==========================================
- Hits         2391     2241     -150     
+ Misses         86       76      -10

Impacted Files	Coverage Δ
openapi_core/unmarshalling/schemas/factories.py	100% <100%> (ø)	⬆️
...penapi_core/unmarshalling/schemas/unmarshallers.py	95.83% <100%> (ø)	⬆️

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[codecov]

Codecov Report

Merging #212 into master will increase coverage by 0.19%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #212      +/-   ##
==========================================
+ Coverage   96.52%   96.71%   +0.19%     
==========================================
  Files         123      118       -5     
  Lines        2477     2317     -160     
==========================================
- Hits         2391     2241     -150     
+ Misses         86       76      -10     

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8c1e331...e817973. Read the comment docs.