Bump django-rq from 2.3.2 to 2.8.0

Bumps [django-rq](https://github.com/rq/django-rq) from 2.3.2 to 2.8.0.
- [Release notes](https://github.com/rq/django-rq/releases)
- [Changelog](https://github.com/rq/django-rq/blob/master/CHANGELOG.md)
- [Commits](rq/django-rq@v2.3.2...v2.8.0)

---
updated-dependencies:
- dependency-name: django-rq
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -3,7 +3,7 @@ django-cacheops==5.0.1
 djangorestframework==3.11.1
 django-filter==2.3.0
 django-netfields==1.2.2
-django-rq==2.3.2
+django-rq==2.8.0
 django-tables2==2.3.1
 django-taggit==1.3.0
 django-taggit-serializer==0.1.7