Deprecation warning for jsonschema @ 4.0.0

[nikitagashkov]

Hello @p1c2u, thanks for your library. I've recently performed a scheduled dependencies upgrade and encountered the following warning:

...

  /Users/.../lib/python3.9/site-packages/jsonschema/validators.py:190: DeprecationWarning: Passing a schema to Validator.iter_errors is deprecated and will be removed in a future release. Call validator.evolve(schema=new_schema).iter_errors(...) instead.
    warnings.warn(

-- Docs: https://docs.pytest.org/en/stable/warnings.html

Looks like jsonschema starting from v4.0.0 deprecates one of theirs API used: https://github.com/Julian/jsonschema/releases/tag/v4.0.0

[p1c2u]

It will be fixed in version 0.5.x which is dependent on jsonschema4+
Version 0.4.x will support jsonschema 3 and 4.