Django-zen-queries

Add new `{% queries_disabled %}` and `{% queries_dangerously_enabled %}` template tags.

* Fix a bug introduced in 2.0.0 with paginated Django REST framework list endpoints (see 33)

* Fix an issue with using zen-queries on unpaginated Django REST framework list endpoints 18 (and see 27)
* Fix an issue where queries were not disabled when using `QueriesDisabledSerializerMixin` on serializers with `many=True` (see 27)
* Low-level implementation converted to use the Database Instrumentation API added in Django 2.0 - no more monkeypatching! 🎉 (see 12)
* Document the use of `zen_queries.TemplateResponse` in Django class-based views 20
* Switch from Travis CI to GitHub Actions
* Packaging improvements

- Include SQL in exceptions https://github.com/dabapps/django-zen-queries/pull/16
- Document template permissions checks gotcha https://github.com/dabapps/django-zen-queries/pull/17