Add outstanding django migrations check

Description

Currently we don't check whether we have any outstanding django migrations before merging to main. We recently implemented a check in IDhub to look for pending migrations. Knowing that many projects within DevOps use django, it could be worth porting this check to the DevOps ci-templates. Example linked below

Task list

• Port functionality over as an extension of django test

Acceptance criteria

• MR pipelines fail if migrations need to be made

Links/references

Original ticket: https://gitlab.developers.cam.ac.uk/uis/devops/iam/idhub/api/-/issues/98

MR: https://gitlab.developers.cam.ac.uk/uis/devops/iam/idhub/api/-/merge_requests/62