Replace deprecated jsonschema.RefResolver with referencing.Registry

[radoering]

Fixes #1786 (which was closed prematurely as pointed out in #1786 (comment))

Fixes the following deprecation warnings:

connexion/json_schema.py:18
  /home/randy/connexion/connexion/json_schema.py:18: DeprecationWarning: jsonschema.RefResolver is deprecated as of v4.18.0, in favor of the https://github.com/python-jsonschema/referencing library, which provides more compliant referencing behavior as well as more flexible APIs for customization. A future release will remove RefResolver. Please file a feature request (on referencing) if you are missing an API for the kind of customization you need.
    from jsonschema import Draft4Validator, RefResolver

connexion/json_schema.py:19
  /home/randy/connexion/connexion/json_schema.py:19: DeprecationWarning: jsonschema.exceptions.RefResolutionError is deprecated as of version 4.18.0. If you wish to catch potential reference resolution errors, directly catch referencing.exceptions.Unresolvable.
    from jsonschema.exceptions import RefResolutionError, ValidationError  # noqa

See also https://python-jsonschema.readthedocs.io/en/latest/referencing/#migrating-from-refresolver

[chrisinmtown]

Thanks for this, I'm a little tired of seeing those warnings every time I run tox. I hope someone can explain why the code test pipeline/workflow didn't run automatically on this PR, only the read-the-docs check?

[chrisinmtown]

I think the imports are grouped (1) python standard, (2) third party and (3) connexion. FWIW maybe it's worth sorting within categories (1) and (2) here?

[radoering]

There is a sorting within categories: At first normal imports sorted alphabetically, then from imports sorted alphabetically.

If I change the order isort will complain.

[chrisinmtown]

Thanks for explaining, I didn't spot that pattern, never mind!

[chrisinmtown]

Would you please consider adding pydoc for this new function?

[radoering]

Done.

[chrisinmtown]

The referencing library is in status Alpha and their issues board includes a ticket about very slow performance:

python-jsonschema/referencing#178

Did you notice any slowdown here?

[radoering]

Did you notice any slowdown here?

I did not notice any slowdown in the tests. I did not try with larger schemas.

[radoering]

I hope someone can explain why the code test pipeline/workflow didn't run automatically on this PR, only the read-the-docs check?

The workflow requires approval from a maintainer according to https://github.com/spec-first/connexion/actions