chore: uplift redis container from v3 to v7 as rq 2.0.0 drops below v4

Author: duttonw

.github/workflows/test.yml

@@ -54,7 +54,7 @@ jobs:
           - 5432:5432
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
       redis:
-          image: redis:3
+          image: redis:7
     env:
       CKAN_SQLALCHEMY_URL: postgresql://ckan_default:pass@postgres/ckan_test
       CKAN_DATASTORE_WRITE_URL: postgresql://datastore_write:pass@postgres/datastore_test