Missing dependency on packaging in django-csp 4.0b3

[titouanc]

Following the update from 4.0b2 to 4.0b3 in our project (based on Python 3.10), the CI is now failing because of the following error:

$ python manage.py collectstatic
File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 883, in exec_module
File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
File "/usr/local/lib/python3.10/site-packages/csp/apps.py", line 3, in <module>
    from csp.checks import *  # noqa: F403 (here to register the checks)
File "/usr/local/lib/python3.10/site-packages/csp/checks.py", line 12, in <module>
    from packaging.version import Version
ModuleNotFoundError: No module named 'packaging'

This looks related to the changes introduced in e9e4e27

I fixed the issue by manually adding packaging to our dependencies, but the proper fix would be to include it in django-csp's own dependencies