pass getattr() for settings to the settings module

[Mike Brancato]

When the Settings class loads the global settings, it roughly does the following.

1. Uses importlib to instantiate the settings module.
2. Iterates thru the upper-case attributes of the module.
3. Assigns the value of the module attribute to an attribute on the Settings class instance.

setting_value = getattr(mod, setting)

This effectively makes dynamic settings impossible. There are probably many use cases for settings which change during runtime, my use-case is dynamic credentials that rotate periodically. So I've used features from PEP-562 (requires Python 3.7) to make certain attributes of a module dynamic. The only requirement really is that getattr() be called on the module.

Is there any reason that the Settings class could not instead maintain a list of settings and use a __getattr__ method to check known settings and pass those to the module?