stevedore ftbfs in the jammy release pocket

[Matthias Klose]

as seen in a test rebuild, this package fails to build in the jammy release pocket (note the log behind the link might go away):

https://launchpadlibrarian.net/604215651/buildlog_ubuntu-jammy-amd64.stevedore_1%3A3.5.0-0ubuntu1_BUILDING.txt.gz

[...]
FAIL: stevedore.tests.test_extension.TestExtensionProperties.test_extras
stevedore.tests.test_extension.TestExtensionProperties.test_extras
----------------------------------------------------------------------
testtools.testresult.real._StringException: Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/stevedore/tests/test_extension.py", line 278, in test_extras
    self.assertEqual(['[extra]'], self.ext1.extras)
  File "/usr/lib/python3.10/unittest/case.py", line 845, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/usr/lib/python3.10/unittest/case.py", line 1051, in assertListEqual
    self.assertSequenceEqual(list1, list2, msg, seq_type=list)
  File "/usr/lib/python3.10/unittest/case.py", line 1033, in assertSequenceEqual
    self.fail(msg)
  File "/usr/lib/python3.10/unittest/case.py", line 675, in fail
    raise self.failureException(msg)
AssertionError: Lists differ: ['[extra]'] != ['extra']

First differing element 0:
'[extra]'
'extra'

- ['[extra]']
? - -

+ ['extra']

----------------------------------------------------------------------
Ran 92 tests in 0.564s

FAILED (failures=1, skipped=1)