Fixed CI Support with Python 3.12 (celery#8611)

* Fixed t/unit/tasks/test_result.py::test_del()

* Skip t/unit/tasks/test_result.py::test_del() if running with PyPy

* Added Python 3.12 to integration tests in the CI

.github/workflows/python-package.yml

@@ -75,7 +75,7 @@ jobs:
       strategy:
           fail-fast: false
           matrix:
-              python-version: ['3.8', '3.9', '3.10', '3.11']
+              python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
               toxenv: ['redis', 'rabbitmq', 'rabbitmq_redis']
 
       services:

t/unit/tasks/test_result.py

@@ -1,5 +1,6 @@
 import copy
 import datetime
+import platform
 import traceback
 from contextlib import contextmanager
 from unittest.mock import Mock, call, patch
@@ -389,12 +390,17 @@ def test_ready(self):
 
         assert not self.app.AsyncResult(uuid()).ready()
 
+    @pytest.mark.skipif(
+        platform.python_implementation() == "PyPy",
+        reason="Mocking here doesn't play well with PyPy",
+    )
     def test_del(self):
         with patch('celery.result.AsyncResult.backend') as backend:
             result = self.app.AsyncResult(self.task1['id'])
+            result.backend = backend
             result_clone = copy.copy(result)
             del result
-            assert backend.remove_pending_result.called_once_with(
+            backend.remove_pending_result.assert_called_once_with(
                 result_clone
             )