Project's core arches dependency range defined in two places

[jacobtylerwalls]

Defining a project-level dependency in core arches can happen in two places:

• pyproject.toml, as of 7.6
• settings.py: MIN_ARCHES_VERSION, and MAX_ARCHES_VERSION

Instead of having this in two places, which can cause drift, we could move the check in compatibility.py out of template rendering and into a Django system check. This probably still has value as a check, since not every developer pip install's their own projects, especially if they're not redistributing their app as a reusable app or doing custom development, or using GitHub etc.

If the check is defined at the project level, we can put it in the apps.py that will exist as of #11016.

[jacobtylerwalls]

Fixed in #11189