Wagtail 4.2 upgrade

[katdom13]

• Include changes from this PR: https://github.com/wagtail/wagtail-autocomplete/pull/130
• Added Wagtail 4.2 compatibility
• Added tests for Python 3.10 and 3.11
• Remove support for versions of Wagtail < 4.1 (Wagtail 4.1 or later now required)

Note: It is important that this PR be merged first (https://github.com/wagtail/wagtail-autocomplete/pull/130) as it provides support for Wagtail 4.0 while this current PR removes support for versions of Wagtail older than 4.1

All tests run OK

collected 24 items                                                                                                                                                                                   

wagtailautocomplete/tests/test_autocomplete_views.py .............                                                                                                                             [ 54%]
wagtailautocomplete/tests/test_edit_handlers.py ...........                                                                                                                                    [100%]

[nickmoreton]

@katdom13 You might want to consider closing this PR. I closed the v4.0 upgrade with a comment of:

I'm closing this PR as I don't believe it required. The package works OK on wagtail up to v5 when I use it on an upgrade site.

[katdom13]

Hi @nickmoreton , closing this. Thanks!