Use collections.abc instead of collections
There are multiple ways to go about this, since collections.abc was introduced in Python 3.3 we don't need to worry about backporting (we only support Python 3.6+). We could
1. Replacing all collections with collections.abc (https://github.com/Sage-Bionetworks/synapsePythonClient/pull/745)
2. import the Callable (e.g from collections.abc import Mapping
This was merged and is part of the 2.1 RC.