v0.4.0

• Add support for related models. See Document Classes and
  Document Field Reference for more information
  (Contributed by Colin Seifer).
• django-opensearch-dsl now only tests supported version of Python and Django (mainstream and LTS).
  This choice is made to:
  • Speed up development.
  • Speed up tests.
  • Reduce actions on github.
  • Encourage people to update their stack to supported (thus safer) versions.
• Drop support for Python 3.6.
• Drop support for Django 2.1, 2.2, 3.1.
• Now supports Django 4.1.
• Now supports opensearch-dsl>=2.0 <3.00.