feat: Add django 4.1 and Python 3.11 support

[fsbraun]

Description

This PR adds tests for Django 4.1 and Python 3.11

Related resources

• The size argument to was_modified_since() has been removed (https://docs.djangoproject.com/en/4.1/releases/4.1/#miscellaneous)

Checklist

• [x] I have opened this pull request against master
• [x] I have added or modified the tests when changing logic
• [x] I have followed the conventional commits guidelines to add meaningful information into the changelog
• [x] I have read the contribution guidelines and I have joined #workgroup-pr-review on Slack to find a “pr review buddy” who is going to review my pull request.

[codecov[bot]]

Codecov Report

Merging #1321 (05467b2) into master (62551a1) will decrease coverage by 0.44%. The diff coverage is n/a.

:exclamation: Current head 05467b2 differs from pull request most recent head 3564799. Consider uploading reports for the commit 3564799 to get more accurate results

@@            Coverage Diff             @@
##           master    #1321      +/-   ##
==========================================
- Coverage   72.21%   71.76%   -0.45%     
==========================================
  Files          72       66       -6     
  Lines        3239     3124     -115     
  Branches      468      511      +43     
==========================================
- Hits         2339     2242      -97     
+ Misses        734      729       -5     
+ Partials      166      153      -13     

Impacted Files	Coverage Δ
filer/server/backends/default.py	100.00% <ø> (ø)
filer/urls.py
filer/views.py
filer/apps.py
filer/migrations/0001_initial.py
filer/__init__.py
filer/settings.py

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[stefanw]

I've deployed Django Filer with Django 4.1 (thinking Django-CMS 3.11.1 support for Django 4.1 would mean Filer would also support it).

Just a heads up: I've found an issue with Filer Admin popups using Django 4.1. Here's the PR: https://github.com/django-cms/django-filer/pull/1326