Limit psycopg2 version to 2.8.6

For version >2.9 of psycopg2, it is impossible to do 'CREATE DATABASE' in context managers (unfortunately it is done in Albion when creating a project).

See https://stackoverflow.com/questions/68084078/psycopg2-errors-activesqltransaction-create-tablespace-cannot-run-inside-a-tran for details and useful links.