CI unit testing has failures under 3.12.1

[woodsp-ibm]

The nightly CI runs have been failing for the last few nights under Python 3.12 - mainly Ubuntu but it did do it with Mac too (Windows has no 3.12 runs yet - see #108)

E.g. https://github.com/qiskit-community/qiskit-algorithms/actions/runs/7256311824/job/19768394836

  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/site-packages/stestr/subunit_runner/program.py", line 247, in runTests
    self.result = testRunner.run(self.test)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/site-packages/stestr/subunit_runner/run.py", line 51, in run
    test(result)
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/suite.py", line 84, in __call__
    return self.run(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/suite.py", line 122, in run
    test(result)
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/suite.py", line 84, in __call__
    return self.run(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/suite.py", line 122, in run
    test(result)
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/suite.py", line 84, in __call__
    return self.run(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/suite.py", line 122, in run
    test(result)
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/case.py", line 692, in __call__
    return self.run(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/case.py", line 662, in run
    result.stopTest(self)
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/site-packages/subunit/test_results.py", line 127, in stopTest
    return self.super.stopTest(test)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/site-packages/subunit/test_results.py", line 56, in stopTest
    return self.decorated.stopTest(test)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/site-packages/testtools/testresult/real.py", line 1539, in stopTest
    self._tags = self._tags.parent
                 ^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'parent'

And there are numerous warnings about a lack of addDuration in test result e.g.

/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/unittest/case.py:580: RuntimeWarning: TestResult has no addDuration method
  warnings.warn("TestResult has no addDuration method",

A similar issue is noted here too

• Switch from unittest to stestr runner after Windows 3.12 bug is fixed Qiskit/rustworkx#1041

[mtreinish]

I think this will be fixed by: testing-cabal/testtools#371

[woodsp-ibm]

#118 temporarily uses Python 3.12.0 where CI is running unit tests in order to avoid the issue for now. The changes there should be reverted once testtools has been updated/released with the fix linked above.

Update: As Qiskit Aer now supports 3.12 I was able to bump the CI job for max version from 3.11 in #130, but due to this also used specific version 3.12.0. So that aspect of the workflow should be updated too assuming #130 is merged ahead of being able to use just 3.12 and hence allow bug fix releases to be used as they appear.