ImportError: Update collections to collections.abc for Python 3.10 Compatibility

[Amr-00]

Summary
pylogit encounters an ImportError in Python 3.10 because the Iterable class has been moved from collections to collections.abc.

Error Details
When running pylogit in Python 3.10, the following error is raised:

Cause
The error is caused by the following line in choice_tools.py:
from collections import Iterable

In Python 3.10, Iterable is now located in collections.abc, resulting in the ImportError.

Proposed Solution
To fix this issue and ensure compatibility with Python 3.10 and later versions, the import statement should be updated in choice_tools.py:

Update this line
from collections import Iterable

To this line
from collections.abc import Iterable

Testing
After making this change locally, pylogit works correctly without any ImportError in Python 3.10.

Request
Please update the import statement to (from collections.abc import Iterable) in the relevant files for Python 3.10 compatibility.