Add Python 3.10 support
Using or importing ABCs from 'collections' instead of 'collections.abc' has been deprecated, and it's finally removed in python 3.10. python-leather relies on these collections, therefore it fails to run on python 3.10
Using or importing ABCs from 'collections' instead of 'collections.abc' has been deprecated, and it's finally removed in python 3.10. python-leather relies on these collections, therefore it fails to run on python 3.10