openlineage: do not try to redact Proxy objects from deprecated config

[mobuchowski]

When preparing AirfowRunFacet we're iterating over Context. This access cause warnings:

[2023-08-14, 09:02:53 UTC] {warnings.py:109} WARNING - /usr/local/lib/python3.11/site-packages/airflow/utils/context.py:314: AirflowContextDeprecationWarning: Accessing 'next_ds' from the template is deprecated and will be removed in a future version. Please use '{{ data_interval_end | ds }}' instead.
  warnings.warn(_create_deprecation_warning(k, replacements))
[2023-08-14, 09:02:53 UTC] {secrets_masker.py:277} WARNING - Unable to redact <Proxy at 0x7f07121b14c0 wrapping '2023-08-14' at 0x7f0712137770 with factory functools.partial(<function lazy_mapping_from_context.<locals>._deprecated_proxy_factory at 0x7f071216d260>, 'next_ds', '2023-08-14')>, please report this via <https://github.com/apache/airflow/issues>. Error was: TypeError: ObjectProxy() missing required argument 'wrapped' (pos 1)

This PR removes direct access to those objects, and redacting it when Proxy is encountered. We can't remove iteration over dict, so in this case we're suppressing this error. In case of Proxy we'll skip serializing the object anyway.