Fixup compatibility with Python 3.10

[ignatenkobrain]

collections.Iterable was moved to collections.abc.Iterable in Python 3.8
but compatibility was preserved. In Python 3.10, old path was removed.

[mburtless]

👋 thanks for the contribution! Unfortunately as is this will break compatibility with python 2.7 which still needs to be maintained. I think we'll either need to utilize the six module here or something like

try:
    from collections.abc import Callable  # noqa
except ImportError:
    from collections import Callable  # noqa

[istr]

This has been addressed in v0.18.0.

[shane-ns1]

Since the fix @mburtless suggested was implemented, I'm going to close this ticket. Thanks for pointing out the issue and giving a fix!