Schemathesis

- 2382577 Move OpenAPI-specific code to `schemathesis.specs.openapi._hypothesis`

- fa10801 Refactoring & comments
- deee01b Remove unneeded condition
- 7396949 Remove deprecated ``_accepts_context`` internal function
- d204391 Remove deprecated `skip_validation` argument to `HookDispatcher.apply`
- 93f3cfe Changelog entry formatting

:package: Other

- f4ce014 Remove parametrization over Open API spec version where it is not needed
- e854e5b Add Open API 3.0 test app
- e37a5d3 Fix flaky test

- 885a03e Update pre-commit hooks
- 3dc5e08 Statically guarantee that the output of `get_strategies_from_examples` will not contain `None` values
- 812b1fc Downgrade `actions/checkout` to v1 for `commitsar` job
- fb5fb23 Update `codecov/codecov-action` to v1.0.7
- aa5374b Update `actions/setup-python` to v2
- ab3fcde Update `actions/cache` to v2
- 1b8994e Update `actions/checkout` to v2
- 620376d Remove deprecated code

:package: Other

- 084ba6b Improve readability
- 2536498 Add missing changelog entry