chore(core)!: drop unused ViewPassesTestMixin

The ViewPassesTestMixin was used some time ago in the former
detail_generic module which was dropped. Its not used anywhere else, so
it seems fine to just drop it. Marking this as a breaking change
nonetheless, to downstream projects using this are aware.

apis_core/core/mixins.py

@@ -1,36 +1,4 @@
 from django.conf import settings
-from django.contrib.auth.mixins import AccessMixin
-
-from apis_core.utils.utils import access_for_all
-
-
-class ViewPassesTestMixin(AccessMixin):
-    """
-    Deny a request with a permission error if the test_func() method returns
-    False. This is mostly a copy of Django's UserPassesTestMixin, but it allows
-    to set the APIS_VIEW_PASSES_TEST setting to define a function that receives
-    the view and can perform checks on any of the views attributes.
-    If such a setting does not exist, it falls back  to APIS' access_for_all
-    function.
-    """
-
-    def test_func(self):
-        if hasattr(settings, "APIS_VIEW_PASSES_TEST"):
-            return settings.APIS_VIEW_PASSES_TEST(self)
-        # fall back to more general access check
-        return access_for_all(self, viewtype="detail")
-
-    def get_test_func(self):
-        """
-        Override this method to use a different test_func method.
-        """
-        return self.test_func
-
-    def dispatch(self, request, *args, **kwargs):
-        view_test_result = self.get_test_func()()
-        if not view_test_result:
-            return self.handle_no_permission()
-        return super().dispatch(request, *args, **kwargs)
 
 
 class ListViewObjectFilterMixin: