v0.6.0

[qcoumes]

• Add mananage.py opensearch index update subcommand to update an existing index mappings (#52).
• Add CelerySignalProcessor as an alternative to RealTimeSignalProcessor to process signals asynchronously using Celery
  (#51).
• Add registry.get_models() and registry.__contains__() methods (#48, Contributed by ghkdxofla - Taelim Hwang (Limy)).
• When using the opensearch command, any error now displays the raw OpenSearch response (#49).
• Autosync and related model features are now properly documented (#53).
• Update the test matrix to work with the latest supported version of Python, Django, and OpenSearch. Also, add isort and
  bandit to CI (#50).

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This discussion was created from the release v0.6.0.