Add validation of params next url
Required flake8 and test fixing to get working but actual change is minor.
Part of https://gitlab.developers.cam.ac.uk/uis/devops/raven/admin/-/issues/392
Required flake8 and test fixing to get working but actual change is minor.
Part of https://gitlab.developers.cam.ac.uk/uis/devops/raven/admin/-/issues/392