make use of 'num' in MixPanel backend
make use of 'num' in MixPanel backend

Signed-off-by: Flavio Curella <f88bd2f5363ca9fae8ca8e7b9ecf2a2c5af9874c@gmail.com>

frankwiles/django-app-metrics,jbl2024/django-app-metrics-no-celery,frankwiles/django-app-metrics,pivotal-energy-solutions/django-app-metrics,pivotal-energy-solutions/django-app-metrics,jbl2024/django-app-metrics-no-celery