Update frozen Swashbuckle dependency to latest version and remove patched SchemaGenerator

[bkoelman]

Updates JsonApiDotNetCore.OpenApi to depend on the latest version of Swashbuckle. Removes the patched SchemaGenerator, because the inheritance fix was integrated in Swashbuckle itself.

QUALITY CHECKLIST

• [x] Changes implemented in code
• [x] Complies with our contributing guidelines
• [x] Adapted tests
• [x] Documentation updated

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.28%. Comparing base (cdca6e0) to head (6c9e049).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## openapi #1548 +/- ## =========================================== + Coverage 90.80% 91.28% +0.47% =========================================== Files 397 396 -1 Lines 13023 12800 -223 Branches 2076 2022 -54 =========================================== - Hits 11826 11684 -142 + Misses 781 725 -56 + Partials 416 391 -25 ```

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