Update postgresql instructions for Postgresql 15

[jarppiko]

Postgres 15 does not allow creation of tables in public (default) schema without super-user access rights. crowdsec has to be made the owner of the public schema first. See https://stackoverflow.com/questions/74110708/postgres-15-permission-denied-for-schema-public.

Public schemas are also in version 14 and 13, but the required access rights have been changed in 15.0.

[jarppiko]

https://www.postgresql.org/docs/15/ddl-schemas.html#DDL-SCHEMAS-PRIV

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[LaurenceJJones]

These instructions backwards compatible? for any pg < 15?

Also thank you! for opening a PR

[jarppiko]

@LaurenceJJones Apologies, I have not tested this with other than pg 15. The Postgresql docs say:

A user can also be allowed to create objects in someone else's schema. To allow that, the 
CREATE privilege on the schema needs to be granted. In databases upgraded from 
PostgreSQL 14 or earlier, everyone has that privilege on the schema public. 

But, stupid me. I did not check what Postgresql versions Crowdsec supports (PostgreSQL 10, 11 and 12)...

Therefore, maybe this PR should be put on hold until Crowdsec decides to officially support Postgresql versions higher than 12?

PS. I have been running Crowdsec with Postgresql 13 without problems . I am in progress setting up Crowdsec to run inside rootless container and thought using the latest Postgresql without checking the supported versions. I can report back my success rate, but I understand you guys want to run proper integration testing with the Postgresql newer versions before officially supporting those.

[mmetc]

Thanks! The current version supports PG 15, with tests