Generate migration script

[Kludex]

I was able to create the first migration file via:

kubectl exec users-deployment-7d89d7b668-9kvxz -- alembic revision --autogenerate -m "First migration"
kubectl exec users-deployment-7d89d7b668-9kvxz -- cat /app/migrations/versions/dc304df8db88_first_migration.py >> dc304df8db88_first_migration.py 

Run this by hand is too primitive.

As a plus: decide what approach to take about the "way to run migrations". Some references below:

• https://markgituma.medium.com/kubernetes-local-to-production-with-django-3-postgres-with-migrations-on-minikube-31f2baa8926e
• https://andrewlock.net/deploying-asp-net-core-applications-to-kubernetes-part-7-running-database-migrations/