Merge branch 'bump-django-rq' into 'master'

Bump Python requirement django-rq to 2.4.0

See merge request !1071

requirements.txt

@@ -8,7 +8,7 @@ django-admin-hstore-widget==1.1.0
 django-cors-headers==3.5.0
 django-enumfields==2.0.0
 django-redis==4.12.1
-django-rq==2.3.2
+django-rq==2.4.0
 djangorestframework==3.11.1
 elasticsearch-dsl>=6.0.0,<7.0.0
 gitpython==3.1.11