TestFixture.test_get_hashes fails in Python 3.12

Hi,

Building the python-oslo.versionedobjects package in Debian Sid, with Python 3.12 as available interpreter version (meaning the unit tests are run with 3.11 and 3.12), I get the below unit test failure:

======================================================================
FAIL: oslo_versionedobjects.tests.test_objects.TestFixture.test_get_hashes
oslo_versionedobjects.tests.test_objects.TestFixture.test_get_hashes
----------------------------------------------------------------------
testtools.testresult.real._StringException: Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/oslo_versionedobjects/tests/test_objects.py", line 611, in test_get_hashes
    self.assertEqual('1.6-fb5f5379168bf08f7f2ce0a745e91027',
  File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 394, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 481, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: !=:
reference = '1.6-fb5f5379168bf08f7f2ce0a745e91027'
actual = '1.6-33df6764eb28348018ac966b9697d855'

Given the comment of the unit test:

        # NOTE(danms): If this object's version or hash changes, this needs
        # to change. Otherwise, leave it alone.

I'm blacklisting the unit test in the package. However, it'd be nice to fix it ASAP upstream too.

Cheers,

Thomas Goirand (zigo)