Fix for Python >= 3.3

[tjlaboss]

Since Python3.3, collections.Mapping has been moved to collections.abc.Mapping. The old location was finally deprecated in Python 3.10.

This PR does the following:

• Checks whether the Python version is at least 3.3.
• If it is, import from Mapping from collections.abc instead of collections.
• Increment the version from 0.1.3 to 0.1.4.