Move away from migra

[ewan-escience]

We have been using migra to automatically generate migration scripts for consecutive releases of the RSD (sometimes having to adapt them manually). However, Migra hasn't been updated in 2 years and it is starting to fail in some cases. For example, it didn't see the newly added DOMAIN in this PR.

So we need to move to another tool. Ideally it works the same as migra: take two running databases and create s script that when applied to one of the databases, would update its schema to be the same as the other database.

[ewan-escience]

Some tools to consider:

• Atlas looks promising
• pgdiff is similar but hasn't been updated in 3 years
• pg-schema-diff also looks promising, but it isn't clear if you can run it agains two running databases (compared to one running database and one schema file)
• pg-diff seems not to be actively developed anymore
• PostgresCompare is not free