Upgrade to 2022.03 fails because of postgresql error during docker-compose up

[QSchulz]

I cannot update from 2021.03 to 2022.03 because my master node (named lava-server) fails to boot with the following error message:

lava-server_1     | Starting postgresql
lava-server_1     | Starting PostgreSQL 13 database server: mainError: /var/lib/postgresql/13/main is not accessible or does not exist ... failed!

@montjoie reported to have had the same issue when persistent_db is set to True in the master node and removing it "fixes" the issue.

Updating with persistent database is therefore currently not supported as far as I understood.

[montjoie]

You could udpate until a major postgresql version change.
I will update documentation on this.

[montjoie]

Documentation update via #172