PyImath.PyImath{,Numpy}Test_Python3 tests fail with Python 3.11a06

[hobbes1069]

23/38 Test  #2: PyImath.PyImathNumpyTest_Python3 ........***Failed    0.04 sec
Traceback (most recent call last):
  File "/builddir/build/BUILD/Imath-3.1.5/src/python/PyImathNumpyTest/pyImathNumpyTest.in", line 8, in <module>
    from imath import *
    ^^^^^^^^^^^^^^^^^^^
SystemError: type Boost.Python.enum has the Py_TPFLAGS_HAVE_GC flag but has no traverse function

29/38 Test  #1: PyImath.PyImathTest_Python3 .............***Failed    0.11 sec
Traceback (most recent call last):
  File "/builddir/build/BUILD/Imath-3.1.5/src/python/PyImathTest/pyImathTest.in", line 8, in <module>
    from imath import *
    ^^^^^^^^^^^^^^^^^^^
SystemError: type Boost.Python.enum has the Py_TPFLAGS_HAVE_GC flag but has no traverse function

From the bugzilla report:
The PyType_Ready() function now raises an error if a type is defined with the Py_TPFLAGS_HAVE_GC flag set but has no traverse function (PyTypeObject.tp_traverse). (Contributed by Victor Stinner in bpo-44263.)

https://bugzilla.redhat.com/show_bug.cgi?id=2069676

[hobbes1069]

This appears to be more of a boost python bug. Feel free to close or leave it as a tracking bug. I'll close it when it's fixed upstream.

[vstinner]

I proposed boostorg/python#385 to update Boost Python (enum type) to Python 3.11.