Updates for py312 compatibility

- Added py312 section to tox.ini [testenv]
- Updated flake8 to 7.1.1 instead of 3.9.2
- Updated unit tests for py312 compatibility

Change-Id: I1f9c130e18aea6a17edeb955ae3649ce370d8df7

tox.ini

@@ -56,6 +56,13 @@ deps =
     -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 
+[testenv:py312]
+basepython = python3.12
+deps =
+    -c {env:TEST_CONSTRAINTS_FILE:https://raw.githubusercontent.com/openstack-charmers/zaza-openstack-tests/master/constraints/constraints-2024.1.txt}
+    -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+
 [testenv:py3]
 basepython = python3
 deps =
@@ -65,7 +72,7 @@ deps =
 
 [testenv:pep8]
 basepython = python3
-deps = flake8==3.9.2
+deps = flake8==7.1.1
        git+https://github.com/juju/charm-tools.git
 commands = flake8 {posargs} hooks unit_tests tests actions lib files
            charm-proof

unit_tests/test_actions.py

@@ -92,7 +92,7 @@ class PauseTestCase(CharmTestCase):
                 return True
 
         self.service_pause.side_effect = maybe_kill
-        self.assertRaisesRegexp(
+        self.assertRaisesRegex(
             Exception, "haproxy didn't stop cleanly.",
             actions.actions.pause, self.args)
         self.assertEqual(pause_calls, ["swift-proxy"])
@@ -146,7 +146,7 @@ class ResumeTestCase(CharmTestCase):
                 return True
 
         self.service_resume.side_effect = maybe_kill
-        self.assertRaisesRegexp(
+        self.assertRaisesRegex(
             Exception, "apache2 didn't start cleanly.",
             actions.actions.resume, self.args)
         self.assertEqual(resume_calls, ['swift-proxy', 'memcached'])
@@ -294,7 +294,7 @@ class DiskUsageTestCase(CharmTestCase):
         self.check_output.assert_called_once_with(['swift-recon', '-d'])
 
         self.action_set.assert_called()
-        self.action_fail.not_called()
+        self.action_fail.assert_not_called()
 
     def test_check_output_failure(self):
         """Ensure that action_fail and action_set are called on