Upgrade to Django 4 + upgrade CKEditor5 to CKEditor6

Django 2.2 -> Django 3.2

• Defining the default auto field required in Django 3.2 in settings.py

Django 3.2 -> Django 4.2

• force_text depreciated -> force_str
• ALLOWED_HOSTS must be a list or tuple
• Upgrade custom django_ckeditor_5 to public django_ckeditor (v6.5)
• Fixed unit and functional tests