xmlutils module not compatible with Python 3.10

The rapid_pe.xmlutils module is incompatible with Python 3.10 because it attemps to import Iterable from collections. This object was moved to collections.abc for Python 3 and the backwards-compatible shim removed in Python 3.10:

$ PYTHONPATH=$(pwd) python ./bin/rapidpe_integrate_extrinsic_likelihood --help
Traceback (most recent call last):
  File "/home/duncan/git/rapidpe/./bin/rapidpe_integrate_extrinsic_likelihood", line 41, in <module>
    from rapid_pe import lalsimutils, factored_likelihood, mcsampler, xmlutils, common_cl
  File "/home/duncan/git/rapidpe/rapid_pe/xmlutils.py", line 19, in <module>
    from collections import namedtuple, Iterable
ImportError: cannot import name 'Iterable' from 'collections' (/home/duncan/opt/mambaforge/envs/py310/lib/python3.10/collections/__init__.py)