Updated reference to Django main branch (#393)
Updated reference to Django main branch (#393)

The branch was renamed from master to main. Additionally, the latest version dropped compatibility with Python 3.7 and below. 
rodgomes/django-waffle,rsalmaso/django-waffle,rodgomes/django-waffle,rsalmaso/django-waffle,rsalmaso/django-waffle,rodgomes/django-waffle,willkg/django-waffle,willkg/django-waffle,rsalmaso/django-waffle,rodgomes/django-waffle