Update to SQLAlchemy 2.0

[martinburchell]

SQLAlchemy 1.4 is marked as legacy and at the time of writing is still being maintained. I can't see any mention of an end-of-life date. So this is low priority for now.

My understanding is that SQLAlchemy 2.0 has a more simplified API to earlier versions, meaning there are fewer ways to achieve the same end and leading to more consistent code.

So we should work towards migrating to 2.0. Fortunately this need not be done all at once. See https://docs.sqlalchemy.org/en/14/changelog/migration_20.html

[martinburchell]

@RudolfCardinal I'm going to start work on this unless you've already done so.

[RudolfCardinal]

Thanks! No, haven't done this yet. Some comments on the CRATE process at https://github.com/ucam-department-of-psychiatry/crate/blob/sqlalchemy2/devnotes/2025_01_sqlalchemy2_databricks/notes_sqlalchemy2.txt