fails to start on python 3.10.1

excalibur fails to load with python version 3.10.1 giving the below error :

```
Traceback (most recent call last):
File "/home/murali/.local/bin/excalibur", line 5, in
from excalibur.cli import cli
File "/home/murali/.local/lib/python3.10/site-packages/excalibur/cli.py", line 7, in
from . import __version__, settings
File "/home/murali/.local/lib/python3.10/site-packages/excalibur/settings.py", line 10, in
from . import configuration as conf
File "/home/murali/.local/lib/python3.10/site-packages/excalibur/configuration.py", line 7, in
from backports.configparser import ConfigParser
File "/home/murali/.local/lib/python3.10/site-packages/backports/configparser/__init__.py", line 130, in
from collections import MutableMapping
ImportError: cannot import name 'MutableMapping' from 'collections' (/usr/lib/python3.10/collections/__init__.py)
```