Invalid RELEASE_CHECK_URL never raises an error

[jathanism]

NetBox version

v2.10.6

Python version

3.8

Steps to Reproduce

1. Define settings.RELEASE_CHECK_URL to an obviously invalid URL
2. Start the server (such as with manage.py runserver

Expected Behavior

A ValidationError should be raised that results in an ImproperlyConfigured error.

Observed Behavior

No errors are raised.

It appears that the use of URLValidator to check the validity of the defined URL is not being used correctly and so a ValidationError will never be raised.