Mistral Python 3.10 collections errors

Mistral gets several collections abstract base class errors with 'tox -e py310'. For example:

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FAIL: mistral.tests.unit.engine.test_workflow_cancel.WorkflowCancelTest.test_fail_then_cancel_with_items_child_workflow
mistral.tests.unit.engine.test_workflow_cancel.WorkflowCancelTest.test_fail_then_cancel_with_items_child_workflow
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testtools.testresult.real._StringException: Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/mistral/tests/unit/engine/test_workflow_cancel.py", line 588, in test_fail_then_cancel_with_items_child_workflow
    self.engine.start_workflow('wb.wf')
  File "/<<PKGBUILDDIR>>/mistral/db/utils.py", line 109, in decorate
    return retry.call(_with_auth_context, auth_ctx, func, *args, **kw)
  File "/usr/lib/python3/dist-packages/tenacity/__init__.py", line 411, in call
    return self.__call__(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/tenacity/__init__.py", line 423, in __call__
    do = self.iter(retry_state=retry_state)
  File "/usr/lib/python3/dist-packages/tenacity/__init__.py", line 360, in iter
    return fut.result()
  File "/usr/lib/python3.10/concurrent/futures/_base.py", line 438, in result
    return self.__get_result()
  File "/usr/lib/python3.10/concurrent/futures/_base.py", line 390, in __get_result
    raise self._exception
  File "/usr/lib/python3/dist-packages/tenacity/__init__.py", line 426, in __call__
    result = fn(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/mistral/db/utils.py", line 57, in _with_auth_context
    return func(*args, **kw)
  File "/<<PKGBUILDDIR>>/mistral/engine/post_tx_queue.py", line 80, in decorate
    res = func(*args, **kw)
  File "/usr/lib/python3/dist-packages/osprofiler/profiler.py", line 160, in wrapper
    result = f(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/mistral/engine/default_engine.py", line 61, in start_workflow
    wf_ex = wf_handler.start_workflow(
  File "/usr/lib/python3/dist-packages/osprofiler/profiler.py", line 160, in wrapper
    result = f(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/mistral/engine/workflow_handler.py", line 48, in start_workflow
    wf.start(
  File "/usr/lib/python3/dist-packages/osprofiler/profiler.py", line 160, in wrapper
    result = f(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/mistral/engine/workflows.py", line 158, in start
    dispatcher.dispatch_workflow_commands(
  File "/usr/lib/python3/dist-packages/osprofiler/profiler.py", line 160, in wrapper
    result = f(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/mistral/engine/dispatcher.py", line 127, in dispatch_workflow_commands
    _process_commands(wf_ex, wf_cmds)
  File "/<<PKGBUILDDIR>>/mistral/engine/dispatcher.py", line 149, in _process_commands
    task_handler.run_task(cmd)
  File "/usr/lib/python3/dist-packages/osprofiler/profiler.py", line 160, in wrapper
    result = f(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/mistral/engine/task_handler.py", line 73, in run_task
    task.run()
  File "/usr/lib/python3/dist-packages/osprofiler/profiler.py", line 160, in wrapper
    result = f(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/mistral/engine/tasks.py", line 568, in run
    self._run_new()
  File "/usr/lib/python3/dist-packages/osprofiler/profiler.py", line 160, in wrapper
    result = f(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/mistral/engine/tasks.py", line 600, in _run_new
    self._schedule_actions()
  File "/<<PKGBUILDDIR>>/mistral/engine/tasks.py", line 852, in _schedule_actions
    with_items_values = self._get_with_items_values()
  File "/<<PKGBUILDDIR>>/mistral/engine/tasks.py", line 912, in _get_with_items_values
    if not isinstance(items, collections.Iterable):
AttributeError: module 'collections' has no attribute 'Iterable'