[fix] Fixed placement of "openwisp_radius" in INSTALLED_APPS
[fix] Fixed placement of "openwisp_radius" in INSTALLED_APPS

DRF does not respect the settings defined in openwisp_radius.apps
if openwisp_radius is placed after djangorestframework in
INSTALLED_APPS.
nemesisdesign/ansible-openwisp2,openwisp/ansible-openwisp2