Broken on Python 3.10, uses deprecated collections.Callable

[nylanderdev]

The alias collections.Callable for collections.abc.Callable has been deprecated. The alias is used in __init__.py, and therefore httplib2shim (and dependants like GEE) do not work on Python 3.10. See python/cpython#23754

Proposed change: Change the single occuring instance of collections.Callable to collections.abc.Callable.
Problem: This might break the library for anyone using Python <3.3, so it is potentially both a patch and a breaking change, making it unclear what the SEMVER should be.

See nylanderdev@7344d5d

[nylanderdev]

Could always check version manually and create alias for python versions >=3.10