upgrade code to django 4.2.1 and python 3.8.10 (testing env versions)

[JulianDroske]

applied patches i commited before.

[xiaohuanshu]

Good job.I took a quick look at that, and I found a few problems.

1. requirements.txt needs to be updated
2. python manage.py check need to be handled
3. In settings.py, "from checkinsystem.settings_env import *" is not good, you can use an environment variable to point to settings_env or settings_local if you want run some test. eg:

if os.getenv('LOCAL_SETTINGS', None):
    import importlib
    local_settings = os.getenv('LOCAL_SETTINGS')
    mdl = importlib.import_module("checkinsystem." + local_settings)
    if "__all__" in mdl.__dict__:
        names = mdl.__dict__["__all__"]
    else:
        names = [x for x in mdl.__dict__ if not x.startswith("_")]
    globals().update({k: getattr(mdl, k) for k in names})
elif os.path.exists(os.path.join(DIRNAME, "local_settings.py")):
    from checkinsystem.local_settings import *