Add Apitally to Third Party Packages in docs

[itssimon]

Add Apitally to the Third Party Packages page in the docs, under Misc.

Apitally is a simple, lightweight API monitoring and analytics tool for DRF that helps developers track API usage, performance, and errors with minimal setup. It also includes request logging and alerting features.

See setup guide here: https://docs.apitally.io/frameworks/django-rest-framework