FTBS in jammy: FAIL: magnumclient.tests.test_shell.ShellTest.test_help_on_subcommand

This failure is due to a change in python 3.10 where the string "optional arguments" was changed to "options", more info at https://docs.python.org/3/whatsnew/3.10.html#argparse and https://bugs.python.org/issue9694 .

Upstream bug: https://storyboard.openstack.org/#!/story/2009946
Upstream fix: https://review.opendev.org/c/openstack/python-magnumclient/+/835217

Test failures:

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FAIL: magnumclient.tests.test_shell.ShellTest.test_help_on_subcommand
magnumclient.tests.test_shell.ShellTest.test_help_on_subcommand
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testtools.testresult.real._StringException: Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/magnumclient/tests/test_shell.py", line 127, in test_help_on_subcommand
    self.assertThat((stdout + stderr),
  File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 480, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: 'usage: magnum bay-create [--name <name>] --baymodel <baymodel>\n [--node-count <node-count>]\n [--master-count <master-count>]\n [--discovery-url <discovery-url>]\n [--timeout <timeout>]\n\nCreate a bay. (Deprecated in favor of cluster-create.)\n\nOptions:\n --name <name> Name of the bay to create.\n --baymodel <baymodel>\n ID or name of the baymodel.\n --node-count <node-count>\n The bay node count.\n --master-count <master-count>\n The number of master nodes for the bay.\n --discovery-url <discovery-url>\n Specifies custom discovery url for node discovery.\n --timeout <timeout> The timeout for bay creation in minutes. The default\n is 60 minutes.\n' does not match /.*?^Optional arguments:/

======================================================================
FAIL: magnumclient.tests.test_shell.ShellTestKeystoneV3.test_help_on_subcommand
magnumclient.tests.test_shell.ShellTestKeystoneV3.test_help_on_subcommand
----------------------------------------------------------------------
testtools.testresult.real._StringException: Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/magnumclient/tests/test_shell.py", line 127, in test_help_on_subcommand
    self.assertThat((stdout + stderr),
  File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 480, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: 'usage: magnum bay-create [--name <name>] --baymodel <baymodel>\n [--node-count <node-count>]\n [--master-count <master-count>]\n [--discovery-url <discovery-url>]\n [--timeout <timeout>]\n\nCreate a bay. (Deprecated in favor of cluster-create.)\n\nOptions:\n --name <name> Name of the bay to create.\n --baymodel <baymodel>\n ID or name of the baymodel.\n --node-count <node-count>\n The bay node count.\n --master-count <master-count>\n The number of master nodes for the bay.\n --discovery-url <discovery-url>\n Specifies custom discovery url for node discovery.\n --timeout <timeout> The timeout for bay creation in minutes. The default\n is 60 minutes.\n' does not match /.*?^Optional arguments:/