django admin broken after 4.2 upgrade

[devincowan]

Our django admin is broken as of hs 2.15.8

See this issue:
stephenmcd/mezzanine#2054

Internal Server Error: /admin/theme/siteconfiguration/1/change/
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "/usr/local/lib/python3.9/site-packages/django/core/handlers/base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/contrib/admin/options.py", line 688, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/utils/decorators.py", line 134, in _wrapper_view
    response = view_func(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/views/decorators/cache.py", line 62, in _wrapper_view_func
    response = view_func(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/contrib/admin/sites.py", line 242, in inner
    return view(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/mezzanine/utils/admin.py", line 60, in change_view
    response = super().change_view(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/contrib/admin/options.py", line 1889, in change_view
    return self.changeform_view(request, object_id, form_url, extra_context)
  File "/usr/local/lib/python3.9/site-packages/django/utils/decorators.py", line 46, in _wrapper
    return bound_method(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/utils/decorators.py", line 134, in _wrapper_view
    response = view_func(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/contrib/admin/options.py", line 1747, in changeform_view
    return self._changeform_view(request, object_id, form_url, extra_context)
  File "/usr/local/lib/python3.9/site-packages/django/contrib/admin/options.py", line 1792, in _changeform_view
    form_validated = form.is_valid()
  File "/usr/local/lib/python3.9/site-packages/django/forms/forms.py", line 201, in is_valid
    return self.is_bound and not self.errors
  File "/usr/local/lib/python3.9/site-packages/django/forms/forms.py", line 196, in errors
    self.full_clean()
  File "/usr/local/lib/python3.9/site-packages/django/forms/forms.py", line 435, in full_clean
    self._post_clean()
  File "/usr/local/lib/python3.9/site-packages/django/forms/models.py", line 486, in _post_clean
    self.instance.full_clean(exclude=exclude, validate_unique=False)
  File "/usr/local/lib/python3.9/site-packages/django/db/models/base.py", line 1470, in full_clean
    self.clean_fields(exclude=exclude)
  File "/usr/local/lib/python3.9/site-packages/django/db/models/base.py", line 1522, in clean_fields
    setattr(self, f.attname, f.clean(raw_value, self))
  File "/usr/local/lib/python3.9/site-packages/mezzanine/core/fields.py", line 54, in clean
    return escape(value)
  File "/usr/local/lib/python3.9/site-packages/mezzanine/utils/deprecation.py", line 71, in wrapper
    return django_safe(s(*args, **kwargs))
  File "/usr/local/lib/python3.9/site-packages/mezzanine/utils/html.py", line 113, in escape
    protocols=ALLOWED_PROTOCOLS + ["tel"],
TypeError: unsupported operand type(s) for +: 'frozenset' and 'list'

Looks like this needs to be updated to:
protocols=list(ALLOWED_PROTOCOLS) + ["tel"],

Or possibly, we need to downgrade Bleach from 6.1.0 to bleach==5.0.1