Migrations and model changes

Here is a scenario.

1. You change a model in laguna-backend-model crate.
2. You also change the corresponding migration in migrations dir.
3. Your migration is now out of sync with DB.
4. Run scripts/dbreset.sh laguna_dev_db which drops current laguna_dev_db, recreates new laguna_dev_db and runs all migrations.

Here is another way to do it (without dropping DB):

1. You change a model in laguna-backend-model crate.
2. You create a new migration in migrations crate using sqlx migrate add <migration_name> which contains some ALTER statements which probably have DEFAULTs.
3. You run sqlx migrate run to run all migrations.

It is also possible to create "reversible" migrations with sqlx migrate add -r <migration_name> which will create an up and down migration files and can be reverted with sqlx migrate revert.